Sargeant, Alonso and Magnussen are the latest converts to the medium tyre as the front runners continue to pound around on the test C4s. Albon uses them to go fastest on a 1m20.075s.
We've known all season that the Williams is rapid in a straight line, and that could prove a potent weapon here with the long main straight. Albon has just gone purple in sector one on his way to setting the third fastest time, as Verstappen goes fastest on a 1m20.085s.
Ricciardo, Piastri and Gasly are running the hards, while Hamilton and Bottas are running the mediums. Everybody else, as mentioned, is on the test tyres.
The vast majority have elected to use the test compound for the early stages in the session. As a reminder, it's a prototype C4 compound that Pirelli is evaluating with the hope of offering a wider working range and improved mechanical assistance to reduce graining. You can identify it by the tyre having no coloured sidewall.
A little under five minutes away from the session starting. We're into the eighth edition of F1 racing at Mexico in the track's current configuration, 60 years after its first world championship grand prix won by Jim Clark in 1963 from Jack Brabham and Richie Ginther.
But for everybody else the show continues and as the track rubbers in we'll get a better idea about who is capable of setting consistent times over longer stint lengths. However, the race on Sunday will start three hours earlier than today's FP2 session, so the track conditions won't be exactly comparable.
Today will be a day that Hadjar and Ollie Bearman never forget, while the same can be said for Fred Vesti who also made his F1 weekend bow at Mercedes.
For this writer it was rather surreal seeing Isack Hadjar take part in FP1. I was at Paul Ricard for the Volant Winfield driver assessment in February 2019 when a 14-year-old Hadjar - notably smaller than most of the drivers in attendance - was selected as the best under-15-year-old and earned as his prize a free entry to the final French F4 round of that year.
For Tsunoda, his first track running of the weekend will take on a greater significance with the knowledge he'll be starting from the back after taking a fifth gearbox and a new suite of power unit components. Race set-up is always of paramount importance, but he at least won't have to worry about getting a car dialled in for quali trim.
After stepping aside for FP1, George Russell, Pierre Gasly, Yuki Tsunoda, Kevin Magnussen and Valtteri Bottas will have some catching up to do at the Mexico City track.
After that interlude, we're back to bring you all the build up to FP2 in a little over 20 minutes when normal service will resume with the full complement of regular drivers back aboard their cars.
And with that, it's time for us to disappear for a couple of hours before FP2 begins at 23:00. As ever, thank you for joining us and if you need to catch up, here is the full session report!
Toto Wolff explains that Mercedes were going through plenty of test items during FP1 and that Hamilton made an error on his fast lap. Had that not been the case, he expects Hamilton would have featured in the top three.
As the session ends, the FIA has revealed that Tsunoda will start the Mexico City GP from the back of the grid after fitting a fifth power unit of the year.
After the pace of Mercedes in the US, it is somewhat of a surprise to see Hamilton languishing in P11 and a second off the pace. It is possible that Mercedes were focusing on long-run pace over qualifying speed, but only the team will know the exact details.
Bearman was the fastest of the F2 drivers, besting Alonso on his final tour to go P15. Hadjar (P17), Doohan (P18) and Vesti (P19) round out those that have set times. Pourchaire is the only driver with a blank timesheet.
A wild moment for Bearman through the back chicanes, smashing the kerbs and sliding his Haas all over the place. It ruins his lap but the Briton is pushing hard on his debut.
The battle between McLaren and Ferrari looks as close as ever but Mercedes, so far, look a little off the pace with Hamilton currently in P11, behind Stroll.
With less than 10 minutes remaining, Albon is certainly the standout performer of this session. Yes, it's only FP1, but all being equal, the Williams driver looks set for a strong weekend.
It has been reported that Pourchaire has a brake-by-wire problem and the gearbox is coming off the Alfa Romeo. A horrible session for the F2 points leader.
Albon is on an absolute flier here and improves from P4 to P2! He is 0.095s back on pace-setter Verstappen! The Williams looks to have genuine pace this weekend.
Alonso is finally on the track and has set times after being confined to the garage during the early stages. Doohan is now the slowest runner, although Pourchaire is yet to set a time.
