Rosberg on top in practice

The king of showboating Nico Rosberg repeated his season-long trick of topping the timesheets in practice for Sunday's Turkish Grand Prix.

In the dying seconds of the opening session at Istanbul's Otodrom, Rosberg conjured up his usual late blast on low fuel in his Williams which resulted in the 24-year-old deposing long-time leader Lewis Hamilton from top spot at the end of the 90 minutes by just over three tenths of a second.

Toyota's Jarno Trulli finished third quickest, just eight thousandths of a second behind Hamilton.

Rosberg, who set a time of one minute 28.952seconds for the 5.338km circuit situated 25 miles from the centre of Istanbul, on Thursday 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."

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.

Current championship leader Jenson Button, 16 points clear of team-mate Barrichello and 28 ahead of Vettel, had to settle for 11th as he finished 0.795secs off Rosberg.