Ferrari continues to set the pace at Jerez de la Frontera, albeit in the form of the Ferrari-powered Sauber of Brazilian rookie Felipe Nasr.

On a day which started out damp following overnight rain, meaning drivers either started on full wets or inters, the pace quickened as the eight drivers on duty completed over 700 laps, three of them, Nasr, Nico Rosberg and Carlo Sainz each over one hundred.

Despite the changing conditions and the sheer amount of laps there were just three red flags over the course of the day; the first when Nasr went off into the gravel, the second around midday when Rosberg stopped on track and the third in the final moments of the session when Pastor Maldonado also ground to a halt.

As previously reported, it was a day of mixed emotions for McLaren, which had Fernando Alonso on duty. The Spaniard, having completed 32 laps, six times the amount he managed on Sunday, was side-lined in the afternoon with another technical problem.

"We've had a loss of cooling water pressure and have removed the power unit for inspection," revealed the Woking outfit. "That's a long process, so it ends today's running.

"We can replace those components ahead of running tomorrow," it added. "The issue was promptly spotted by Fernando on an out lap - so quick to trace."

The day was difficult for Red Bull also. The Austrian team, having lost valuable track time yesterday as it had no spare front wing to replace that damaged when Daniil Kvyat went off, was stuck in the garage again for much of today with an engine issue. The presence of team owner Dietrich Mateschitz no doubt adding to the pressure.

Elsewhere, a telemetry problem meant that Pastor Maldonado was late getting to work however, once up and running the Venezuelan was on the pace.

Once again, Williams, which had Felipe Massa on duty, got on with the job in hand, doing the sort of quiet preparation we have grown used to on Friday's, ‘softly, softly' appearing to be the Grove outfit's new mantra.

With his teammate having dominated on the opening two days of the test, Kimi Raikkonen looked set to make it a hat-trick however, despite trading fast laps with Nasr and Rosberg, eventually had to settle for second, 0.205s off the pace, the Finn looking very much as ease with the SF15-T.

Once again, the Toro Rosso drivers have looked impressive, Sainz adding another 136 laps to the team's tally on his way to the sixth best time of the day.

All in all, an interesting day, and one which - should the form be carried over in to the season - set us up for a real thriller. That said, the Mercedes still appears to be the class of the field. Indeed, on his final lap, as he headed back to the pits, Rosberg, who hands over to teammate Lewis Hamilton for the final day tomorrow, told his crew: "Thank you everyone... a really top start to the year."

With the track still damp in the morning, Nasr ran on wet tyres as well as on slicks to make some comparisons. With dry conditions in the he used different dry compounds and completed 108 laps on his way to posting the fastest time of the day.

"It was another positive day," said the Brazilian. "We did a lot of mileage, and we were able to get a better understanding of the car. On top of that, we used different tyres in different conditions, and we played with the set-up. In the end I had the chance to do some long-runs to get a feeling for the car with high fuel loads like they would be in race conditions. It was important for me to get used to all these different things.

"Overall they were two very positive days," he concluded. "I'm glad that I already feel comfortable in the new environment, and I'm really happy with everything I've seen so far with the team. I'm already looking forward to Barcelona."

"The day was a bit more complicated than the previous two," said Giampaolo Dall'Ara, the team's Head of Track Engineering. "In the morning it was mainly down to the weather conditions. When the track was still damp we decided to test different wet tyres, and make some comparisons. In the afternoon we continued with the set-up work and some additional scans. We lost a little bit of time with a minor technical issue, but, nevertheless, we were able to complete more than 100 laps. In the end we can be satisfied with the day."

"It's too early to talk about results," said Raikkonen, who spent the day focussing on aero and set-up work, "but we are going in the right direction. There is still a great deal to do, however this has been a positive start, very different to a year ago. A good job has been done on the car with a lot of improvements. Even though these are only early days for testing, we have done plenty of laps, after Sebastian got through two good days of work."

"We had a better day in terms of reliability and with Kimi we managed a good number of tests," added James Allison. "It was interesting to get his feedback on the handling characteristics of the SF15-T, when compared to last year's car."

Mercedes programme comprised long runs and practice pit stops, Rosberg Nico emerging for his first run at 09:00 and completing 93 laps before lunch and a further 58 in the afternoon. His running was briefly interrupted when the W06 was brought to a halt by an engine cut at T10 just before 13:00.

"Reliability was our main issue over the last year," said Rosberg, "so our goal for 2015 is to sort this out. That is why I can be happy with my first pre-season test as I did a lot of mileage on both days. A big thank you to the team for a reliable Silver Arrow so far. They did a really good job over the winter.

"Performance wise I don't know where we are but the Ferrari times look very encouraging for them, so it will be an interesting year for Formula One, I guess.

"However," he continued, "I recently heard about the discussions concerning the German Grand Prix and it's really sad for me and the German fans to hear that nothing is confirmed yet for 2015. For as long as I can remember, the German Grand Prix was part of the Formula One World Championship, so I really hope our Grand Prix will be held this year and beyond that. The fans deserve to have a great show every year because there are so many great supporters out there. Also there is plenty of Germany in F1, with us German drivers like Sebastian, Hulk and myself, plus of course Mercedes-Benz. So I really hope that Bernie and the promoters find a good solution for everybody."