San Francisco Frontiers - Verstappen on top again as McLaren struggle, Piastri 12th

The four-time world champion kept the pressure on as he clocked a best lap of one minute and 17.392 seconds to outpace the Monegasque by 0.153 seconds with Mercedes teenage rookie Kimi Antonelli third ahead of Lando Norris in the leading McLaren.

Seven-time champion Lewis Hamilton was fifth in the second Ferrari, 0.300 off the pace, but maintaining the improvement of recent weeks.

But series leader Oscar Piastri struggled to make an impression in his once-supreme McLaren and wound up 12th, eight-tenths adrift of Verstappen, whose recent run of hot form has lifted him to within 40 points of the Australian.

Norris, second in the title race, is 14 points behind Piastri, but both are hampered by McLaren's decision to stop updating their car while Red Bull and Ferrari continue developments and catch them.

Since the end of August, Piastri has seen a lead of 104 points over Verstappen slashed as the champion reeled off three wins and two seconds in five races with Norris edging closer without conviction.

Mercedes also remain a threat and George Russell was sixth ahead of Yuki Tsunoda in the second Red Bull, two-time champion Fernando Alonso of Aston Martin, Williams' Carlos Sainz and Lance Stroll in the second Aston Martin.

Liam Lawson was 11th and was first out for Racing Bulls on a glorious sunlit day at the Autodromo Hermanos Rodriguez with all the teams at full strength after nine rookies had been drafted in during the earlier opening session topped by Leclerc.

Russell soon set a top time before being outpaced by Antonelli and then Leclerc, demonstrating that Ferrari have found some encouraging pace with a lap in 1:18.669.

Norris, bidding to overhaul team-mate Piastri's 14-point advantage in the championship, complained of "a lot of misfire... out of every corner, a lot of surges," suggesting possible engine issues.

He was within 0.012 of Leclerc as they all ran on mediums, many of the leading drivers finding the limits after missing the earlier run, with Hamilton third in the other Ferrari with Norris between them in second and Verstappen fourth and Piastri fifth.

It was clearly a tight contest between the leading group with McLaren struggling to recover their lost supremacy after abandoning car development, having won the constructors' title.

"Our 2026 project would have been heavily compromised if we had continued with updates," said team boss Andrea Stella. "We want to win championships in the future and to win championships in the future you need to have a competitive car...

"Don't forget that as champions, we are the most restricted by the regulations in terms of the wind tunnel allowance... It's not like we have unlimited resources that we can use."

- 'Just no grip' -

By mid-session, Leclerc had cut his time to 1:17.545 on softs to lead ahead of the two McLarens with Piastri struggling to match Norris's pace, both six-tenths adrift -– and then Verstappen, the only man still on mediums, banged in a flyer in 1:17.392 to go clear by 0.153.

After an unscheduled off-track excursion, Hamilton was slower to move to softs for qualifying simulation laps and when he did he slotted in fifth behind Verstappen Leclerc, Antonelli and Norris -– representing four different teams.

With 20 minutes to go, Piastri was down in 12th and eight-tenths adrift of the Red Bull pace. The top ten were all within six-tenths of the Dutchman, a scenario suggesting the Melburnian driver needed a significant improvement.

Most then switched to long run tests of different tyres, some hoping the softs would hold up long enough to enable them to avoid using the hard in Sunday's race.

Verstappen, on softs, then slid at Turn Four, complaining "there's just no grip."

Like Piastri and Norris, he knew that tyres were likely to be a key factor in Sunday's 71-lap showdown with all the top teams capable of finding the speed on the evidence of Friday’s action.

D.Brown--SFF