Valtteri Bottas has emphasised that the small margins at the Brazilian Grand Prix means Mercedes cannot feel comfortable with its position atop the pecking order.
Bottas led Mercedes team-mate Lewis Hamilton following the conclusion of Friday’s running, as the team strives to clinch a fifth straight Constructors’ Championship.
The pair were separated by just 0.003s while Ferrari’s Sebastian Vettel finished just 0.073s adrift in third, with lead Red Bull runner Daniel Ricciardo only three-tenths back.
“We really improved the car for the afternoon and I managed to find a rhythm,” said Bottas, who was sixth in the opening practice session.
“The pace seemed to be good, but it is a short track, so the margins are small.
“There was not a lot of tyre drop-off today, but we're expecting warmer temperatures, so we will have to wait and see if that might bring about some issues.
“It is very close between the top three teams, so we can't feel satisfied about our results today.
“We know everyone else is going to be working on their performance overnight, so we will have to keep pushing as well.”
Hamilton added: “It's been a relatively normal day, we got through everything we needed to.
“The car felt better than it did in Mexico, but we are still working our way through some issues.
“The pace doesn't seem too bad, so we just have to keep working on it and improving it.
“It's very close between all of us at the front, but I think there's more potential in our car, so we just need to try and squeeze it out.”