Brazilian GP: Lewis Hamilton beaten by Valtteri Bottas in practice
Valtteri Bottas led Lewis Hamilton to a Mercedes one-two in second practice at the Brazilian Grand Prix.
Bottas was just 0.003secs quicker than Hamilton, and Ferrari's Sebastian Vettel was just 0.073secs off the pace in third.
But Ferrari, who still have hopes of wresting the constructors' championship from Mercedes, showed much stronger pace in race trim.
Renault's Nico Hulkenberg had a heavy crash at the tricky Juncao corner.
The tight left-hander is one of the most important bends on the track, as it leads on to the long, uphill pit straight. Hulkenberg ran a little wide and kept his foot down as the car ran off the kerb on to the grass, which pitched him into the wall.
The incident brought out the red flag for six minutes as the wreckage was cleared.
It was the only major incident in the session.
The Red Bulls of Daniel Ricciardo and Max Verstappen were fourth and fifth, ahead of Ferrari's Kimi Raikkonen, with Haas' Romain Grosjean best of the rest ahead of Sauber's Charles Leclerc.
The champion's not happy
Hamilton, who is determined to break a run in which he has never won another race in a season after clinching the championship early, did not sound satisfied with the Mercedes' performance, complaining about tyres over the radio to the team a number of times through the session.
"It's been a normal day," he said. "We got through everything we needed to. The car felt better than in Mexico but we still have some problems we are trying to work our way through and understand, but the pace doesn't seem too bad so we just have to keep working on it."
Although Mercedes had a slight edge on one-lap pace, Hamilton's speed on the race-simulation runs was worrying - Vettel was on average about 0.5secs a lap faster.
But the Ferrari was also struggling with tyres - Vettel's rears displayed blisters on long runs on both the super-softs and softs.
Mercedes are in a strong position in the constructors' championship - they will win it on Sunday, a race early, as long as Ferrari do not score 12 more points than them.
But they are concerned about their slip in pace since Hamilton's victory in the Japanese Grand Prix and are keen to return to winning ways and to ensure they understand what happened in the previous two races in Austin and, particularly, Mexico.
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Vettel said: "The car still doesn't feel good, but if we get the balance in the window, it can be tight. We are in the ballpark but I think we can still launch forward from where we are.
"The biggest worry was a little screw that came loose and was somewhere between my feet. We found it in the end.
"Tyres were still sort of OK, ours looked pretty bad. But it's Friday, if it's hotter on Sunday - which it is supposed to be - it will be more of a challenge."