Red Bull duo wary of Ferrari's form

Ferrari's Fernando Alonso set the pace in the second practice session on Friday, outpacing Vettel by less than 0.030.

Alonso's team-mate Felipe Massa completed a positive day for the Italian squad after setting the third fastest time.

"Ferrari looks extremely competitive and I think McLaren probably had a difficult day today with only one car for the majority of the training so we will see tomorrow," said Vettel after managing 26 laps in the afternoon session.

Webber was fourth quickest and the Australian also reckons Ferrari is competitive.

"The car felt pretty good. We have some work to do tonight. Ferrari look strong, so we have some competition this weekend and are looking forward to the race," said Webber.

Vettel admitted, however, that the changing weather conditions made it hard to judge the times from today's sessions.

"It was slippery today obviously," he said. "The conditions were changing all the time, so to really judge the lap times is quite difficult because you have to see when everyone was out on the circuit and in which conditions. But it was important to get some dry running in the afternoon I think and it looked quite promising.

"The car feels nice, especially in the last section, so all in all it is a good day. Ferrari looked very quick and McLaren had a difficult day in the office, with only one car for a majority of the running, but I am sure they will be back up there tomorrow. It is tight."