Nico Rosberg set the pace in second practice at the Brazilian Grand Prix, after losing out to team-mate Lewis Hamilton in the first session.
The German was 0.458 seconds quicker than Hamilton, who had a similar advantage in the morning.
Ferrari’s Sebastian Vettel was nearly a second slower in third place ahead of team-mate Kimi Raikkonen and Red Bull’s Daniel Ricciardo.
Williams’ Valtteri Bottas was sixth, ahead of Romain Grosjean’s Lotus.
Hamilton had had what he described as a “difficult week”, including a fever and crashing one of his supercars in the early hours of Tuesday in Monaco, and delayed his trip to Brazil by a day.
But the world champion says he is determined to win this race for the first time – and to end a run of four consecutive pole positions for Rosberg, which culminated in victory in Mexico at the last race.
At this early stage, Mercedes appear unchallenged, although the gaps between the cars will almost certainly reduce on Saturday over the short lap of the Interlagos track, where margins are normally tight.
BBC F1 analyst Allan McNish said: “It looks like Vettel and Raikkonen are going to be competitive during the race, but on Saturday it will be all Mercedes.”
Ricciardo was running an upgraded version of the Renault engine and initial impressions appeared positive – he was just 0.085secs slower than Raikkonen and nearly 0.3secs ahead of team-mate Daniil Kvyat, who was using the previous-spec Renault.
However, Ricciardo said the improvement “doesn’t look like much”. He added: “It’s the first day running it on track and the guys will look and see if there is something we can tune and try and get more power out of it. The positive was it ran all day and we got lots of laps but the power difference for now is not so much.”
Towards the back of the field, engines were also the focus at McLaren – and, as ever this season, it was bad news.
Fernando Alonso stopped out on circuit with an engine problem before he had a chance to do a qualifying-type run on the faster ‘soft’ tyre.
The Honda puffed smoke out of the exhaust, within which flames were visible before Alonso was told to pull off by the side of the track.
Alonso walked dejectedly away from the car and sat, apparently contemplatively, on the barriers by the side of the track as he watched the marshals begin the recovery process.
The session was briefly red-flagged while they removed the car and Alonso was given a lift back to the pits in the medical car.
He ended the session 17th, one place and just under half a second behind team-mate Jenson Button.
Both men are running the new ‘spec four’ Honda engine. Alonso has had problems with both units he has used in the past two races in the US and Mexico.
He said on Thursday the engines had been inspected and were both fine but the one that failed in practice here is the unit he used in Austin and which developed a problem that dropped him from fifth to 11th in the closing laps.
McLaren said it would need to be inspected back at Honda’s base and Alonso would need to use his other engine for the remainder of the weekend.
