Mercedes AMG Petronas
Friday leader Nico Rosberg admitted to a few concerns over tyres during practice for the Brazilian Grand Prix.
Rosberg was fastest in both free practice sessions but says that blistering of the tyres was slightly worrying at a newly resurfaced Interlagos.
"The track has a new surface which made it quite tricky," said Rosberg.
"It's smooth and not quite so bumpy as it has been in the past - but the tyres were blistering because of the high temperatures and the new asphalt. That was a bit worrying, but we are expecting it to be a bit cooler over the weekend."
Mercedes team-mate Lewis Hamilton was a couple of tenths behind Rosberg in second position.
"There are a few improvements we can make but I just didn't manage to put a lap together out there," he said.
"That's not a big issue, though. It's just practice so that's what we're out there trying to do. I'm not sure how many laps we'll get out of the tyres as there were quite a few red flags at the end so we didn't get the best opportunity for long runs but that's the same for everyone.
"It's hard to tell where the tyres are compared to 2013 with the different compounds as we didn't have any dry running until the race last year."
