1. Charles Leclerc (Ferrari) - 1:18.128

2. Kimi Antonelli (Mercedes) +0.659

3. Frederik Vesti (Mercedes) +0.733

4. Lewis Hamilton (Ferrari) +0.738

5. Ayumu Iwasa (Red Bull) +0.985

The virtual safety car is cleared so cars can continue with their various run plans.

At Racing Bulls, Nikola Tsolov is having trouble with his leg. The Bulgarian is stood up in the cockpit, trying to shake out the aches and pains.

Well done, Audi. British rookie Freddie Slater is getting ready to come back out with 11 minutes left of this session.

The yellow flags are out for Aston Martin's Jak Crawford, who has come to a stop on the Mexican track. The American was told by his pit wall to slow down and stop the car, and now the virtual safety car is deployed.

Freddie Slater will be staying in the garage now, but the teenager does get another chance at an FP1 session next weekend in Brazil, so all is not lost for the Briton.

George Russell is watching on for this hour as Frederik Vesti climbs into the top three on his low fuel, soft-tyre run. He's seven tenths away from Charles Leclerc, but there's only a small between himself and championship leader Kimi Antonelli.

Lewis Hamilton has reached Turn 13 on his latest hot lap but the Briton can't wrangle in that prancing horse, so he stays third on the timesheets.

Alpine's Pierre Gasly is doing both sessions today and the frenchman, who banked another point in Austin, is fourth quickest behind Hamilton after his run on the soft compound.

Leonardo Fornaroli is having a tough old session in the McLaren. The 21-year-old Italian is given a list of things his issues could be by the pit wall as he struggles to find the sweet spot in Ladno Norris' car.

Lewis Hamilton gets a flying lap in on the softs but he can't get close to that top marker by Ferrari team-mate Charles Leclerc. The seven-time world champion is a second off the pace in third spot.

Charles Leclerc has dusted off the soft tyres to see if he can put his car back to the top of the timesheets. The Monegasque driver has a shot at claiming second in the standings himself, as he's only nine points off. Mercedes' George Russell.

Soft beats hard so far, as Leclerc goes fastest with a 1:18.128.

Next up on the red rubber is championship leader Kimi Antonelli, who slots into second, 0.659 seconds away from Leclerc's best marker.

Marc Priestley
Ex-F1 mechanic on Radio 5 Sports Extra in Mexico City

You've got to take all these lap times with a slight pinch of salt. Nobody has been pushing for outright lap times - but that will change.

When we get into the second session we'll really see what these teams and drivers can do around here.

Ferrari are not running a rookie in this session, so regular drivers both Lewis Hamilton and Charles are both out on track.

The seven-time world champion is only a point behind George Russell in the fight for second in the standings, and now he's gone above team-mate Leclerc by 0.060 seconds with a time of 1:19.137 on the hard tyre.

The stewards are going to investigate Audi leaving a cooling fan on Freddie Slater's car after the session, and now it looks like the teenager's practice running is over.

The highest rookie of the 10 that are out on track in Mexico is Red Bull's Ayumu Iwasa, who was third on the timesheets before Lewis Hamilton clocked a marker a couple of tenths quicker. But fourth is still good for 25-year-old Japanese driver.

Meanwhile, fellow rookie Freddie Slater is down at the bottom of board, and now the Briton has to come into the pit lane, as he has a cooling fan still attached to his Audi.

Marc Priestley
Ex-F1 mechanic on Radio 5 Sports Extra in Mexico City

This is what this session is - and it's going to hamper the drivers not in the car.

The likes of Verstappen and co, although he'll get up to speed very quickly, but there is so much unknown going into the weekend with these 2026 cars.

It's a huge learning from everybody.

Nikola Tsolov is only seven points off incoming Haas driver Rafael Camara in the Formula 2 standings, and the 21-year-old Bulgarian has been spoken about as a potential replacement for Liam Lawson at Racing Bulls next season.

This is Tsolov's first F1 practice session, and he's not doing too badly with a time of 1:20.661, placing him eighth behind Nico Hulkenberg and ahead of McLaren Oscar Piastri.

Australian Piastri, meanwhile, has just had a moment on his medium tyres.

Image source, FIA

Ferrari, Red Bull and McLaren are among the teams to bring upgrades to the Autodromo Hermanos Rodriguez, but most of the modifcations are small, circuit-specific tweaks for the weekend - nothing major.

Red Bull

Engine cover, sidepod.

Ferrari

Engine cover, cooling louvres.

Racing Bulls

Coke/engine cover, cooling louvres.

McLaren

Colling louvres.

Alpine

Exhaust tailpipe.

Audi

Rear corner.

It looks like Isack Hadjar will be stuck in the garage for a little while, as his Red Bull has a power-unit issue. Team-mate and four-time world champion Max Verstappen has made way for Ayumu Iwasa in this opening practice session, who sits ninth on the timesheets.

Leonardo Fornaroli is taking reigning world champion Lando Norris' car out for a spin, but the Italian has a big twitch at Turn 11, and asks his McLaren pit wall to take a look.

Charles Leclerc was told Ferrari have been picked as favourites for this weekend's Mexico City Grand Prix. "And who are the people?!" he joked in reply. The Monegasque driver was on the podium in Austin last week but he said Mercedes are still the team to beat no matter what track they go to this season.

Just like in Texas, Leclerc is leading the practice session with a time of 1:19.197 on the hard tyre.

Championship leader Kimi Antonelli manages to make a lap stick and goes top of the timesheets with a 1:20.155 on the hard C3 compound.

Nico Hulkenberg in the Audi is four tenths off the Italian in second, with Racing Bulls rookie Arvid Lindblad, who has F2 driver Nikola Tsolov as a team-mate for FP1, third quickest on the board.

Will Oliver Bearman be driving for Haas next season? More than likely. But the British driver still hasn't been confirmed alongside new rookie Rafael Camara. He goes to the top of the leader briefly in Mexico but like Kimi Antonelli before him, his best lap time is deleted for track limits.

Over at Red Bull, Isack Hadjar's troubles continue. The Frenchman had a lot to say over the radio in Austin and now he's got issues again. "Something wrong man. I have no power. What's happening?" he asks his pit wall.

The route to success is pretty simple for Kimi Antonelli.

To overtake Sebastian Vettel in the record books as the youngest F1 world champion (Vettel was 23 when he won his first champoinship in 2010), Antonelli can...

• Finish ninth if George Russell wins the race
• Finish 10th if Lewis Hamilton was to triumph on Sunday
• If neither Russell nor Hamilton seal victory in Mexico, the Italian will be title winner wherever he finishes in Mexico.