Carlos Sainz set the fastest time today, just as he did on the second day last year, though this time he was at the wheel of a Williams.

Please Note: Due to major IT issues we have been out of action since early on Tuesday. We were back online late this afternoon and consequently we are still catching up. We aim for a far more detailed report tomorrow, the final day of the test. Sincere apologies to all our readers.

The Spaniard set a best time of 1:29.348 running the C3 tyre on the 63rd of his 127 laps, a time 0.573 thousandths quicker than his best from 12 months ago. That rounds off his testing as tomorrow, team-mate Alex Albon will drive for the whole day.

Behind Sainz came the two Ferrari drivers who shared the SF-25. Lewis Hamilton was faster than Charles Leclerc by just 0.52 thousandths - 1:29.379 for the Englishman, 1:29.431 for the Monegasque. They too set their best times using the C3 compound.

It was cool once again today with temperatures fluctuating between 13 and18 degrees C, which is definitely unusual for Bahrain, as was the arrival of rain, which meant that the 18 drivers stayed in their garages for quite a while: 18 because Max Verstappen and Alex Albon did not drive today. The only exception was Esteban Ocon who took his Haas for a run on a set of Intermediates, the first time this tyre has been used at Sakhir since testing in April 2017, courtesy of Daniel Ricciardo in the Red Bull. In fact, the French driver just did three practice starts.

In terms of tyre usage, once again today the C3 was the main protagonist, although less obviously so than yesterday: 767 laps, 60.97% of the total 1258, were completed on this compound. Apart from the Intermediate, the other tyre making its first appearance of the season was the C4, which did just 30 laps split between Nico Hulkenberg (Sauber), Sainz and Leclerc. The other compounds used were the C2 (238 laps, 18.92%) and the C1 (210 laps, 16.69%). This increased equilibrium between the three hardest compounds when compared to yesterday, was mainly down to the various race simulations, or at least long runs completed by almost all the drivers. Sainz did the most laps (127) while the longest stint came courtesy of Racing Bull's Japanese driver Yuki Tsunoda, who completed 25 consecutive laps on a set of C1s.

"Despite the unusual sight of rain, we were able to complete most of the intended programme without issue," said Dave Robson, Williams chief engineer. "The car ran reliably again, which is testament to its design and the efforts of all those involved in building it, including the team of mechanics here at the track that work through the nights to prepare the car and the test items.

"Carlos drove the full day today and was able to build on his experience from yesterday to explore more of what the FW47 can do. Rather than complete a race simulation, we chose a higher fuel level to complete running, which gave us a chance to experiment with setup and tyre management.

"The car was working reasonably well today but we know that there will be significant differences between our run plan and that of our competitors. We are well aware that the final timesheet is not representative of how qualifying will play out in Melbourne.

"Alex will take over tomorrow and can build on a very solid platform that Carlos and his team have evolved today. We expect it to be dry and warmer tomorrow but with some challenging wind gusts, which will provide another set of conditions in which to test the FW47."

"It was a very long day here, with us covering a lot of laps," said pace-setter Sainz. "A few stoppages due to the rain and the wind were not ideal to get into the rhythm but overall, we managed to complete a good programme.

"Although timesheets are not fully representative in Pre-season Testing, we made some progress relative to yesterday, improving the balance and overall feeling of the car. However, it doesn't feel like enough testing to be honest.

"Next thing for me is Australia and I wish I had more time to better understand the car and how it reacts to different set up changes. Having said that, I feel as ready as I can be and I can't wait to push flat out already."

As was the case yesterday, Hamilton was first out for Ferrari, gathering more data for the team, but also beginning to push harder to get a better understanding of the new car. The Briton spent the entire time on the C3 tyres, switching between used and new sets. After the stoppage due to the rain, Hamilton was back at work, setting his best time of 1:29.379, making him the fastest of the morning runners. His two day total is 115 laps (622 kilometres).

In the lunch break, the mechanics went through the usual process of adjusting the cockpit settings to Leclerc's liking and he went out shortly after the light at the end of the pit lane turned green.

The Monegasque started off on a used set of C3 tyres, before fitting a new one and picking up the pace. There were again a few more drops of rain, not enough to stop the cars running on track, but enough to impact performance.

He worked through the planned programme including a qualifying and race simulation. His time on his flying lap was 1:29.431 on the C3 compound, even though he also used the softer C4. For the long run, he used the C3, C2 and C1 compounds. Over the past two days, he has driven 155 laps (838 kilometres), bringing the team's total to 270 laps (1460 kilometres).

"It's been another positive day for us," said Hamilton. "We're making strong progress in understanding the SF-25 and learning how to get the most out of it, and the reliability is good so far which is a really positive sign.

"We didn't get to do as much running as we hoped because of the weather, but we have more time on track tomorrow to work through our programme and to build even more comfort in the car. I'm really enjoying working with the team and we're all looking forward to the final push tomorrow."

"It was more tricky today, because of what are unusual weather conditions for Bahrain, with cooler temperatures and even some rain," added Leclerc.

"We ran through our planned programme, but with the conditions changing quickly, it was difficult to draw many conclusions. Tonight we are fully focused on analysing our data and preparing for the last day of testing tomorrow."

"I am getting more comfortable in the car," said Liam Lawson, who was on duty all day for Red Bull. "As part of testing, we were fighting a few teething gremlins with the car through the day, it's all about just learning about the new car.

"A few of our runs were cut short a little bit and we had to deal with the weather too, which wasn't great timings for our run plan, as I imagine was the case for most of the pitlane.

"All this work is extremely valuable going into Melbourne and we feel in a positive place. This is all the most important stuff when it comes to pre-season, this will be the last time I drive the car before Melbourne, to get things right and we are going to take from all of it, to put together the best-balanced car for the first race."

"We decided to do a full day with Liam, to continue to prepare him ahead of the season," added Pierre Wache. "Unfortunately, the weather wasn't great, with some rain at the beginning of the day, so we decided to do a race simulation, to get Liam up to speed with long runs and to check the car for general reliability across race distance.

"In the afternoon, our aim was to understand the car with the C3 compound and the set up options and to also explore the set-up of the car in general. We had wanted to get a total insight into the car today, and understand its full direction, but it was also difficult to judge the performance of the car in these conditions and get a lot of the temperature on the tyres. But Liam responded well today and his feedback was very close to Max's. We have good understandings to take into the final day of Testing now, with Max at the wheel."

"A trickier day due to the weather," said Oscar Piastri, who completed 44 laps on his way to posting the thirteenth best time of the day. "The temperature and rain made it harder to maximise our testing time in my session, but we were still able to work through a lot and achieve a decent amount. I'm looking forward to getting back on track tomorrow afternoon and hopefully pushing the car further to see what we can get out of it before we head to Australia. Overall, it was a productive day."

"Another productive day with good learnings," added Lando Norris. "We were able to get a decent number of laps in with a long run, and I got the feeling of using some different tyre compounds. I think we've learned a lot from that, and getting the experience of doing the full race run was very valuable. Good feelings so far, we've now got one more day to go to make sure we end the week strongly."

"Another productive day, despite the changing conditions," said Andrea Stella. "The brief periods of rain made it challenging at times this morning, which cost some track time for Oscar, but the team did a good job adapting our run plan accordingly. This afternoon, we focused a little more on longer runs, and overall, we have consolidated yesterday's testing with further data as we learn more about the MCL39."

Alonso was the first of the Aston Martin drivers to take to the track. The rain resulted in less running than expected, the Spaniard completing 45 laps spanning over 240km. Stroll took over for the afternoon session. After 57 laps and over 300km covered, he finished the day sixth, with Alonso in P11.

"It's challenging for everybody here with the weather as it is," said Andy Cowell. "Gusty winds, a bit colder, and a little bit of rain this morning. We've all got our coats on. But we're making the most of it. We're getting the car out on track.

"We're learning with all the instrumentation we've got on the car. We've got a range of different mechanical set-up and aerodynamic set-up components that we're running through, and a team of people back in the factory on campus looking at that data and helping us analyse it and make the right decisions going forward."

"We managed to complete most of our programme today despite the challenging conditions," said Alpine's race director, Dave Greenwood. "It is not often it rains in Bahrain and we reacted well to tailor our programme to the changing conditions. The wet track impacted Pierre's running in the morning session, limiting him to 40 laps, which was well short of what we had planned and didn't allow us to complete some of our tests which required stable track conditions. Nevertheless, we were still able to run through some useful tests this morning and he will be back in the car tomorrow afternoon to conclude the three days with plenty of important work to do now in that final session.

"This afternoon we focused on race weekend scenarios for Jack to continue his preparation ahead of Melbourne. Jack will be back on track tomorrow morning looking to keep building his experience and continue developing the A525 package."

The Haas pair accumulated another 135 laps between them as Esteban Ocon picked up from where he left off yesterday to begin the second day's running, with Ollie Bearman later participating in his only afternoon session of the test.

Continuing to build on race performance, the Frenchman's session was a challenging one due to changing weather conditions. The day began with the VF-25 leaving the garage on the Pirelli C2 tire mounted with aero rakes, moving to a baseline run on the C3 compound shortly before light showers covered the circuit. Having brought a set of intermediates and with track running at a premium, Ocon continued his program while the rest of the grid remained in the pits. As the track dried out, further laps on the C3 tire finished the morning session, with Ocon racking up 69 laps, only beaten by Mercedes' George Russell (71).

Bearman took over for the afternoon and after a short run on a used tire, got to work on the C1 compound for the first time this test for his baseline run. Switching to the C3 compound as the sun set in Sakhir, the Brit continued his long run program. Thursday's running came to a premature finish 20 minutes before the end of the session as Bearman had a minor issue on his car that required maintenance - resulting in a final tally of 66 laps on the board.

"There were tricky conditions out there today," said Ayao Komatsu, "so we did the best we could. We largely carried on from yesterday's program and made progress with Esteban this morning. In the afternoon with Ollie, we continued with some test items which we got answers for, which is great. Unfortunately, just before the end of the day we had a slight car issue, so we had to stop running 20 minutes before the end of the session. We'll fix it tonight and get going tomorrow though. I have to say, today's test items and run program - we completed around 80 percent so it's not been bad. Tomorrow, we're going to look at car balance on short run performance in combination with race simulations."

"It was another solid day," added Bearman, "with the wind dropping a bit, the track made a big step from when I drove yesterday so I'm happy to be back in the car.

"We made some good progress on race trim, and although there was a small issue at the end which I lost a bit of running with, we're looking into it, and it should be fine for tomorrow. Yesterday it was hard to judge with the wind and the track being so green but now I have a bit of a better idea and I'm happy, it feels like a continuation of what I've felt over the years with the team, having driven the VF-23 and the VF-24. I'm still feeling very confident with how the long runs went today."

"I've been experiencing it all today, with cold conditions, wind and rain," said Ocon. "We stuck to the long runs, trying to work on our side with Ollie continuing that work into the afternoon. What's very good is that we're on the same page with what needs improving - there's lots of positive as well - but it's important to try and improve what's needed. It's a steep learning curve so early in the season but it's been good so far and trouble-free.

"It's been nice experiencing the car in proper conditions and working with the team on details. I've had my way of working and the teams had theirs, so we need to align and understand each other once I'm inside the car - and that's what we've been doing."

Check out our gallery from Bahrain, here.