Nico Rosberg said he was looking at the Friday timesheets with caution despite leading the way in both of the opening practice sessions ahead of the Brazilian Grand Prix.

The German led the way in both sessions at Interlagos, although rain throughout the day meant that on-track action was limited for teams up and down the paddock.

Reflecting afterwards, Rosberg said he was pleased with his pace on track and was hopeful of taking the fight to Red Bull - even if he urged caution when it came to reading too much into the times.

"Today I had a good start to the weekend, and I was very quick in the rain even though we don't really know about the fuel levels of the other teams," he said. "Therefore we need to read the time sheets with some caution. But generally I have higher hopes now that perhaps we can give Red Bull a hard time this weekend.

"We all know that the weather plays always a big role here at Interlagos and can catch you out. We were not able to run that much but the track feels really great and it was great fun to be out there and find the limit in these difficult conditions."

Mercedes team-mate Lewis Hamilton meanwhile was second quickest although he admitted he wasn't as comfortable with his car in the wet conditions, most notably when heavier rain was falling in the second session.

"The conditions were tricky out there today and it's a real shame for the fans that they didn't get to see more action on track," he said. "Of course, it's frustrating for us drivers to be sitting in the garage for so long but I really feel for everyone who has made the effort to come here to the track. We were able to get some running during the two sessions and that will be useful as the conditions for the rest of the weekend look pretty much the same.

"I'm struggling a little to get the feel of the car in the wet, and that's really been the same for me with our car all season, so we have some work to do overnight to see where we can make improvements. I'd really prefer a dry weekend but that's out of our hands."