Jenson Button made the most of improved weather conditions to post the fastest time in the second practice for the Turkish Grand Prix on Friday, and his McLaren teammate Lewis Hamilton was third quickest.
The two British drivers made the most of improving conditions after morning rain made the Istanbul Park circuit dangerous and slippery, causing Formula One champion Sebastian Vettel to crash unharmed.
Temperatures improved slightly and the track dried out for the afternoon session, when Germany's Nico Rosberg matched his impressive morning with the second quickest time.
Button, the 2009 F1 champion, completed 26 laps and set a best time of 1 minute, 26.456 seconds, while Rosberg clocked 1:26.521 and Hamilton 1:27.033.
Seven-time champion Michael Schumacher and Mark Webber completed the top five.
It was a day of contrasts for McLaren. A bad morning session saw Hamilton fail to post a time after his clutch stuck as he prepared to join the session late.
Button had managed only four laps and was nearly 22 seconds slower than Fernando Alonso, who was fastest in the morning to boost Ferrari's hopes of finally getting a podium place this season.
Alonso could not repeat the performance as a hydraulic problem forced the Ferrari driver back into the pits.
The two-time F1 champion from Spain had spun early in the second session on turn six. He did finish the session on soft tires but could not improve on 11th.
New driver Pastor Maldonado came off the track and the nose of his Williams bumped into the safety barrier. The Venezuelan driver was unhurt but the car needed to be towed away.
Alonso has been struggling this season, failing to finish on the podium in all three races so far. But his strong performance in cool, slippery conditions will have given Ferrari some hope they can challenge in Turkey.
Alonso completed 13 laps and set a fastest lap of 1 minute, 38.67 seconds in an incident-packed morning run, where Schumacher finished with the third fastest time.
The wet conditions at the Istanbul Park track caused problems throughout the morning, with new drivers Paul Di Resta and Maldonado struggling to keep control.
Vettel's first practice was not what he would have anticipated.
He went way out on a right turn and his car slid across the track and into the crash barrier on the other side of the slippery surface.
The German driver began about midway through the session on intermediate tires just as the rain was getting harder, and he was undone on Turn 8 - the longest in Formula One at 640 meters (2,000 feet).
"There was some water on the exit," Vettel said on race radio. "There was nothing I could do."
Debris flew off the car and the wheels were skewed. Vettel waited for track officials to reach him, and his mangled car was towed away. Team members cleared some debris as he went back to the paddock looking stern-faced.
The 23-year-old Vettel, F1's youngest champion, leads Hamilton in the overall standings by 21 points after winning two of the opening three races. Vettel was second behind Hamilton three weeks ago in China.
In the first practice, Renault pair Nick Heidfeld and Vitaly Petrov were fourth and fifth fastest, respectively, but limited themselves to only nine and 10 laps each.
Swiss driver Sebastien Buemi completed the most laps in the morning, managing 22 in his Toro Rosso.