BUDAPEST: Heikki Kovalainen set the fastest lap in the first practice session for the Hungarian Grand Prix on Friday, when newcomer Jaime Alguersuari debuted for Toro Rosso.

Kovalainen led the first session with a best time of 1 minute, 22.278 seconds to edge Nico Rosberg of Williams. McLaren teammate Lewis Hamilton was third.

Mark Webber, coming off his first win in Germany, was fourth ahead of Kazuki Nakajima of Williams.

Alguersuari had the track nearly to himself for the first half hour as he ran 42 laps in his first drive in an F1 car since replacing the fired Sebastien Bourdais earlier this week.

The 19-year-old Spaniard, who will be the youngest driver to start a race on Sunday, was slowest with a lap of 1:24.228.

Overall Formula One leader Jenson Button finished 10th - nearly nine-tenths behind Kovalainen - while teammate Rubens Barrichello was 13th. Sebastien Vettel of Red Bull - Button's closest challenger, who is 21 points back - was a second off the leading pace for 15th.

Practice continues later Friday.