Ahead of this afternoon's session the air temperature is 29.2 degrees C, while the track temperature is 39.2 degrees. It remains bright and sunny.

Bottas was quickest earlier, edging out teammate Hamilton by just 0.045s, however the Finn faces a 5-place grid penalty after taking on a new ICE.

With fellow Mercedes-powered drivers, Stroll and Russell also facing penalties there is concern that Hamilton might yet take another hit, however speaking at the end of FP1, Toto Wolff appeared to play down the issue.

Verstappen was third quickest, almost a second down on the Mercedes pair, as Red Bull continues to lag behind in terms of pace.

Behind Verstappen it was the Ferrari pair and Gasly.

Track limits were an issue with a number of drivers having their times deleting for erring at either Turn 9 or 19.

Bumps don't appear to be so much of a problem this year, but it's still early days.

The lights go green and in no time at all there are 17 drivers on track, a mixture of hards and mediums though Alonso is on softs, the Spaniard having missed much of the opening session.

"Something's come loose at my elbow, I can't turn properly," reports Norris, who is told to pit.

Giovinazzi posts the first time of the afternoon, a 38.355, but this is soon beaten by Ocon, Stroll and Bottas, who crosses the line at 35.887.

No sooner has Hamilton gone second (35.919), than Perez posts 35.883 and Verstappen 35.914. The Bulls, like the Mercedes pair, on mediums.

Bottas improves to 35.764 as Ricciardo improves to sixth (36.525), the Australian, like Alonso, on softs.

"Stupid idiot," says Verstappen after a little silliness from Hamilton. "Ignore it, don't worry about it," he is told. Nonetheless, the Dutchman vents his frustration with an age-old gesture. Meanwhile, teammate Perez goes top with a 35.716.

It's only Friday, but clearly the tension is building between the two title protagonists.

Mazepin complains that his eyes are watering "like crazy", and he needs to change his helmet, while Leclerc complains of "something near the pedals".

After 17 minutes, Russell is the only driver yet to appear.

The Mercedes pair head out on fresh softs as Russell finally posts a time, the Briton going 17th with a 37.490.

On softs, Stroll goes quickest with a 35.561, but Hamilton is already on a hot lap.

Quickest in S3 (only), Bottas goes top with a 35.360, but moments later Hamilton, who is quickest in the first and final sectors, crosses the line at 34.842.

However, his time is subsequently deleted for exceeding the limits at Turn 19.

Despite the fact that his teammate's time was deleted, Bottas is advised that he's losing out to Hamilton in Turns 6 and 7.

With attention fully focussed on qualifying sims, it comes as no surprise that we get the usual silliness as drivers attempt to make space. It also comes as no surprise that Mazepin is one of those causing the most problems, most notably for Verstappen.

A 34.946 sees Perez go quickest, and having gone quickest in S1, Ricciardo crosses the line at 35.547 to go third.

Moments later, Norris posts 35.203 to go second.

Verstappen goes quickest in S1 but backs off in the second sector as he encounters traffic. "Why do we always f****** go in traffic?" he wonders aloud.

Clearly frustrated - isn't he always? - Verstappen pits without setting a representative time.

Following a brief lull the Mercedes pair head out again, this time on mediums, as they look ahead to Sunday.

With 15 minutes remaining, Vettel (19) has completed the most laps, ahead of Gasly (17), Giovinazzi and Latifi (16), Stroll and Raikkonen (15).

While most are on mediums, Ricciardo, Sainz and Gasly opt for softs, while Ocon, Vettel and Mazepin are on hards.

On qualifying pace, Hamilton appears to have the edge over Perez, Bottas and Verstappen, with Norris ahead of Sainz, Leclerc and Ricciardo.

"There's something at the end of the cockpit touching my leg in the corners," reports Ocon.

Onboard footage reveals the severity of Verstappen's understeer issue.

For a brief moment it looks as if Alonso has come to grief. However, as the kitty litter dust settles it becomes clear that as opposed to binning it in the barriers he has merely spun at Turn 19 and travelled backwards through the gravel.

Perez and Raikkonen are the latest to have their times deleted.

The session ends. Perez is quickest, ahead of Norris, Hamilton, Bottas, Ricciardo, Stroll, Leclerc, Verstappen, Sainz and Giovinazzi.

Ocon is eleventh, ahead of Gasly, Alonso, Raikkonen, Vettel, Tsunoda, Schumacher, Latifi, Russell and Mazepin.

Early days, but had he not had his time deleted Hamilton would have been quickest, while, other than track limits, and traffic, the higher temperatures are making it difficult to see the true pecking order at this stage.

That said, it sets us up nicely for the rest of the weekend.

Check out our Friday gallery from COTA, here.