Monte Carlo - Williams driver Nico Rosberg on Thursday set the fastest time in the free practise for Sunday's Monaco Grand Prix. The German posted a time of 1:15.243 minutes for the 3.340 kilometre-long course through the streets of Monte Carlo in the afternoon session.
World champion Lewis Hamilton managed the second fastest time - 0.202 seconds behind, while BrawnGP's Rubens Barrichello had the third fastest time.
In the earlier session Barrichello set the pace with a time of 1:17.189.
Ferrari's Felipe Massa was 0.310 seconds behind his compatriot, while Hamilton, who last year won the race, posted the third- fastest time, 0.389 seconds behind Barrichello.
World championship leader Jenson Button had the eighth-fastest time and followed that up with the fourth fastest-time in the afternoon.
He said that he expected a tough challenge on the weekend. "It is becoming more difficult all the time. The Red Bull team will be very fast in Monaco."
Ahead of the sixth race of the season, BrawnGP driver Button leads the standings with 41 points after winning four of the opening five season-races.
Barrichello is 14 points behind, while Red Bull's Sebastian Vettel, who had pulled into the pits 23 minutes ahead of the end of the first session with an engine failure, is third with 23 points.
Red Bull owner Dietrich Mateschitz said that he expected a lot from Vettel. "If nothing unforeseen happens, Vettel should be able to start from the front row on the grid and manage a podium finish."
