Formula 1 drivers' championship leader Lando Norris pipped McLaren team-mate Oscar Piastri with his final lap of the session to end sole practice at the Brazilian Grand Prix fastest.
Norris's best time, a 1m09.975s set on medium tyres, was 0.023 seconds faster than Piastri's as McLaren enjoyed a significant advantage over the opposition - at least in the headline times.
But that final Norris-Piastri order wasn't necessarily reflective of their peak single-lap pace.
Off the back of two muted weekends in the United States and Mexico, Piastri appeared to be back on song in FP1 at Interlagos when the cars switched to performance running in the final quarter of an hour of the 60-minute session.
He had been 0.278s faster than Norris on their first runs, 0.261s faster on their second ones, and on his final attempt had been 0.190s up on his previous best in the first sector but ultimately failed to improve his time and was pipped by Norris right at the end.
None of McLaren's usual 'big-four' opposition featured at the sharp end, with Mercedes' George Russell the highest-placed of them in sixth.
Russell had been fastest for the majority of the session thanks to his initial benchmark on the hard-tyre runs, but the Mercedes was a much less potent prospect on the medium tyre as he ended the session 0.670s off Norris's time. Russell's team-mate Kimi Antonelli was 10th, one tenth further back.
Red Bull and Ferrari meanwhile propped up the order, occupying 17th-20th.
Max Verstappen bailed out of a soft tyre run that didn't look like it would challenge Piastri's then benchmark as he headed through Juncao late on, then pitted for a front wing adjustment, and did not have a subsequent attempt at a fastest time.
Team-mate Yuki Tsunoda was slowest of all and had the biggest incident of the session, losing a significant amount of running after clouting a barrier on only his fourth lap.
Tsunoda, who is still thought to have some faint hope of retaining his seat for 2026 after Red Bull delayed making a decision on its line-ups, lost 28 minutes of the weekend's sole practice session after spinning while he attempted to keep his foot in on the exit kerb out of Turn 4.
That spat his Red Bull off right and Tsunoda dinged the front-left corner of his car against the barrier. Initially that only appeared to have damaged his front wing, but Red Bull later reported "damage to both the rear wing and front wing of his car" had been sustained.
Tsunoda also drifted across the pit exit line as Liam Lawson's Racing Bulls was exiting the pitlane. That came at the end of a performance run on soft tyres for Tsunoda, who ran out of sync with the rest of the field as a result of his incident.
A low-key FP1 for Ferrari - which declined to do any performance running - left Charles Leclerc 18th and Lewis Hamilton 19th - Hamilton completing a double spin exiting Mergulho at the end of the session and complaining that "the rear hit the floor" as he did so.
All of that allowed Sauber to end FP1 with two cars in the top five. Nico Hulkenberg was the closest challenger to the McLarens, lapping 0.619s off Norris, with Fernando Alonso (Aston Martin) separating him from team-mate and home driver Gabriel Bortoleto.
Between the two Mercedes were Pierre Gasly - who said early in the session his Alpine felt "more alive today than any day in the past months" - Carlos Sainz (Williams) and Racing Bulls' Isack Hadjar.
Results
1 Lando Norris (McLaren) 1m10.975s
2 Oscar Piastri (McLaren) +0.023s
3 Nico Hulkenberg (Sauber) +0.619s
4 Fernando Alonso (Aston Martin) +0.631s
5 Gabriel Bortoleto (Sauber) +0.641s
6 George Russell (Mercedes) +0.670s
7 Pierre Gasly (Alpine) +0.706s
8 Carlos Sainz (Williams) +0.711s
9 Isack Hadjar (Racing Bulls) +0.732s
10 Kimi Antonelli (Mercedes) +0.769s
11 Liam Lawson (Racing Bulls) +0.819s
12 Alex Albon (Williams) +0.832s
13 Esteban Ocon (Haas) +0.931s
14 Ollie Bearman (Haas) +0.986s
15 Lance Stroll (Aston Martin) +1.095s
16 Franco Colapinto (Alpine) +1.185s
17 Max Verstappen (Red Bull) +1.393s
18 Charles Leclerc (Ferrari) +1.518s
19 Lewis Hamilton (Ferrari) +1.551s
20 Yuki Tsunoda (Red Bull) +1.788s
