Current championship leader, Somerset's Jenson Button, had to settle for 11th as he finished 0.795secs off Nico Rosberg in practice for Sunday's Turkish Grand Prix.

The king of showboating, Rosberg, repeated his season-long trick in practice of topping the timesheets.

In the dying seconds of the opening session at Istanbul's Otodrom ahead of Sunday's race, with the clock having ticked past zero, Rosberg conjured up his usual late blast on low fuel in his Williams.

It resulted in the 24-year-old, in his 60th grands prix, deposing long-time leader Lewis Hamilton from top spot at the end of the 90 minutes by just over three tenths of a second.

Rosberg, who set a time of one minute 28.952seconds for the 5.338km circuit situated 25 miles from the centre of Istanbul, yesterday confirmed his practice times "don't count".

"We just run less fuel than everybody else. We look quicker than we are, so it's not important at all," insisted Rosberg, whose highest finish in a race this season has been sixth.

When it was put to him that it looks good, Rosberg, who has now finished on top 10 times in 19 practice sessions, replied: "That's not the reason why we do it.

"We just do it because it's the best way for us to prepare for our weekend."

Hamilton looked strong in his McLaren, although arguably he was on low fuel too as this track is apparently another not suited to his car.

But the reigning world champion, looking to put behind him his disappointment in Monaco when he started at the back of the grid after a crash in qualifying, can feel reasonably satisfied with his morning's work.

Toyota's Jarno Trulli, who along with team-mate Timo Glock also suffered a disaster around the streets of Monte Carlo, finished third quickest, just eight thousandths of a second behind Hamilton.

Red Bull's Sebastian Vettel and Felipe Massa, winner of this race for the last three years in his Ferrari, were fourth and fifth, just under 0.4secs behind Rosberg.

Such is the competitive nature of Formula One these days, the top 13 were covered by a second, which would have been more but for Rosberg's late surge.

Kimi Raikkonen was seventh, with Fernando Alonso eighth and Rubens Barrichello ninth in his Brawn GP, followed by Heikki Kovalainen for McLaren.

The BMW Sauber duo of Robert Kubica and Nick Heidfeld, with the team running a new multiple diffuser in a bid to claw back lost ground on their rivals, showed few signs of improvement as they were 16th and 17th.

Bringing up the rear were the Toro Rosso pairing of Sebastiens Bourdais and Buemi, the latter nearly two seconds down.