ISTANBUL: Nico Rosberg set the fastest lap on Friday in the first practice session for Formula One's Turkish Grand Prix.

The Williams driver was fastest for the 10th time in 19 practice sessions this season with a lap of 1 minute, 28.952 seconds to better McLaren's Lewis Hamilton by three-tenths of a second.

Toyota's Jarno Trulli finished third quickest, ahead of Sebastian Vettel of Red Bull.

Ferrari's Felipe Massa rounded out the top-five, which was all within four-tenths of Rosberg.

Rosberg acknowledged on Thursday that his speed in practice throughout the season owed more to the car being run light on fuel than any other factor.

Championship leader Jenson Button of Brawn GP set the 11th quickest time.

Button has won five of the season's first six races to lead the overall standings with 51 points. Teammate Rubens Barrichello, who placed ninth, is second with 35 points followed by Vettel - the season's only other race winner - on 23.

Ferrari and Red Bull are expected to offer Brawn GP the toughest opposition for Sunday's 58-lap race at the Istanbul Park Circuit, where Massa is looking to win for the fourth straight year.