Friday's fastest Hamilton cautious after practice

Lewis Hamilton kept McLaren at the top of Friday's time sheets at the end of the afternoon session in Hungary.

But the reigning world champion insisted that, despite appearing to be back at the very top after a difficult first half of the season for the British team, he still expects the Red Bulls and the Brawns to have the edge.

Advised by a reporter for Italy's Sky Sport that he seemed in a particularly good mood after topping the ultimate 90 minute session in Budapest, Hamilton replied: "I don't think I'm in a different mood at all.

"For sure we still have a lot of work to do to be quickest."

The Sky Sport reporter noted that while having the headline time, he and his similarly quick teammate Heikki Kovalainen did not seem to spend much time doing crucial long-runs.

"I actually did two long runs, or medium-length runs. The first wasn't very good but the second one was ok, but I won't know how far off (the pace) we are until I get inside and look at the data," Hamilton said.

Red Bull's Mark Webber was fourth quickest despite an hydraulic problem that sidelined him, again ahead of Sebastian Vettel, who struggled with his usual smile in the pitlane after the afternoon session.

"I'm not very happy with the car yet," said the German, "but we'll see what we can do with it tomorrow. It's going to be a very important day."

Also with a low-profile so far are the Brawns, whose Jenson Button was just 13th in the second session. Jarno Trulli pulled to the side of the track with a technical problem in his Toyota.

Debutant Jaime Alguersuari finished his second ever F1 session again last, this time eight tenths slower than his Toro Rosso teammate Sebastien Buemi.

Neither Ferrari was in the top ten, but Williams' Nico Rosberg has been consistently quick so far.