Ahead of today's second session, the air temperature is 22 degrees C, while the track temperature is 43 degrees. It remains bright and sunny.

Valtteri Bottas led a Mercedes 1-2 in this morning's session, however, interestingly, unlike the German team, neither Red Bull or Ferrari tried the ultrasoft rubber.

The session was red-flagged when Alfonso Celis crashed, the Mexican blotting his copybook at his home race.

The Mexican was one of several reserve drivers on duty meaning that Romain Grosjean, Pierre Gasly and Esteban Ocon are in action this afternoon.

Already facing a 35-place grid penalty following an engine change, Stoffel Vandoorne failed to post a time, having only completed 3 laps. Indeed, it's feared his new engine is a no-no which could mean a further demotion.

Despite missing much of the second half of the session, Red Bull insists that Max Verstappen's 'problem' was merely a set-up issue, while Kevin Magnussen was also sidelined for much of the opening phase of the session.

Behind the leading six, Perez was 'best of the rest', with Alonso, Massa and the Renault duo also looking strong.

The cooler temperatures and dusty track surface mean there were a number of offs and excursions across the grass, but only the hapless Celis actually came to grief.

The lights go green and unsurprisingly Vandoorne is like a hare out of the trap. He is followed by Magnussen, Grosjean, Hartley, Ocon and Gasly.

Vandoorne is warned that his front brakes are new and that he needs a good warm-up lap.

Ocon reports that his car is pulling left to right on the straight, this being the car Celis damaged.

A spin for Grosjean in T17, the Frenchman losing the rear of the car over the kerb. Other than flat-spots, the Haas driver picks up a left-rear puncture which quickly escalates to a full delamination which in turn damages the car.

"something is not right," says the Frenchman as he heads back to the pits, the remaining rubber on his car flailing and causing further damage.

The session is red flagged as debris is removed from the track.

Subsequent replays the puncture could have come before the spin.

Meanwhile, teammate Magnussen tops the timesheets (21.669), ahead of Hartley, Gasly, Grosjean, Stroll and Ocon.

Session will re-start at 14:14.

Alonso joins Hulkenberg at the end of the pitlane, with Vandoorne keeping them company.

However, the Belgian isn't going anywhere. He has an issue and has to be rescued by his crew. "The car is going sideways," he reports.

No such issues for his teammate however, Alonso going quickest with a 19.235. Moments later, countryman Sainz goes second (19.807).

A big spin for Hamilton at T11, the Briton doing well to keep it out of the barriers. That's one set of tyres done for the Briton. He is told to keep his speed down while returning to the pits in order that he doesn't cause any damage.

An 18.808 sees Verstappen go top, while Vettel and Raikkonen go third and fourth.

Verstappen was on the softs, while Vettel was on supers.

An 18.905 sees Raikkonen improve to second.

"Something burns, something burns," urges Vettel, "it feels like acid". He subsequently reports that it could be his extinguisher that went off.

Elsewhere, Sainz spins at T3.

Back in the garage, Vettel climbs from his car and it does appear as though he has something on his bottom.

Meanwhile, Stroll has spun at T5. The car rolls back after stopping, and the rear wing brushes the wall.

An 18.769 sees Ricciardo go quickest, the Australian, like his Red Bull teammate, on the softs.

After 30 minutes, Hamilton is the only driver still to post a time.

Perez goes an impressive seventh on the yellow-banded soft rubber.

Hamilton goes quickest with a 17.932, with Bottas slipping into second moments later.

Raikkonen splits the Mercedes duo with an 18.142, the top five still on softs.

PBs in all three sectors see a soft-shod Massa go 8th (19.300).

Another spin for Stroll, this time at T5.

Now Hamilton is back on track on the supersofts.

Now Ricciardo goes quickest, the Australian posting 17.801. Moments later teammate Verstappen goes third. Both are now on the ultrasofts.

"Grosjean will not rejoin FP2," reveals Haas.

Vettel improves to fourth with an 18.051, the German now on the supers.

At half-time, it's: Ricciardo, Hamilton, Verstappen, Vettel, Raikkonen, Bottas, Hulkenberg, Alonso, Sainz and Perez.

A minor lock-up for Vettel in the stadium, with Verstappen following suit moments later. "The engine is doing weird things at pick up," reports the Red Bull driver.

Hartley, on supers, improves to 14th (19.754). However, it appears his teammate has an issue, Gasly is out of his car while the crew work on it, most of them wearing face masks.

As ever, attention has now switched to longer runs, at least for most.

Alonso and Ocon both posts PBs in S1. They maintain the pace in S2, the Spaniard on ultras and the Frenchman on supers. Alonso posts 18.508 to go seventh while Ocon (18.822) remains tenth.

Hartley improves to thirteenth (19.423) on the ultrasofts.

"I haven't put it all together yet," reports Ricciardo, the Australian still topping the timesheets.

Stroll runs wide in the stadium, the Canadian not having the best of days.

Hartley is the latest in a long line of spinner, the Kiwi getting it wrong at T6.

With all the drivers into their race sims, one has to feel for Grosjean and Gasly who have both had limited running in this session after handing over their cars in FP1.

"The engine makes a strange sound on the exit of the apex at T5," reports Hartley.

Ocon has completed the most laps (30), ahead of Hartley (29), Raikkonen and Perez (28).

Check out our Friday gallery from Mexico, here.