Jenson Button was fastest and team mate Lewis Hamilton second as McLaren dominated practice at a wet German Grand Prix on Friday while Michael Schumacher emerged unscathed from an embarrassing crash.
Button and Hamilton both set their times in the morning practice as heavy rain played havoc with the afternoon practice which ended with Schumacher bringing out the red flags.
Pastor Maldonado was fastest for Williams in the second session although the Venezuelan was more than 10 seconds behind Button's time in the first.
Seven-times world champion Schumacher lost control of his car on turn 12 and the vehicle spun out of control across the grass into the barriers in front of the Mercedes stand.
Schumacher emerged unscathed but looking decidedly uncomfortable. He then watched the marshals as they lifted his Mercedes onto a crane.
The session ended at that point, although most of the fans had already left the stands by then looking for somewhere drier.
Intermittent showers had also made conditions tricky for the drivers although the rain was nothing on the scale which caused chaos at the British Grand Prix at Silverstone two weeks ago.
Finnish test driver Valtteri Bottas crashed his Williams near the end of the opening session, smashing into the barriers on corner 13 and emerging unscathed to survey the damage.
Button set the best time of one minute 16.595 seconds early in the session before the rain began while Hamilton, who will be taking part in his 100th grand prix on Sunday, was 0.498 seconds behind.
They were followed by world championship leader Fernando Alonso of Ferrari and Schumacher. However, the conditions meant it was difficult to read anything significant into the timings.
The German Grand Prix, halfway point in the 20 race championship, is seen as crucial to McLaren's season after poor performances in the previous two races saw them slip down the standings to fourth place.
McLaren, winners in Germany last year, have brought a big package of updates to Hockenheim to help them close the gap on leaders Red Bull.
The rain continued after the second practice which was bad news for hundreds of people camped in forests and fields outside the circuit, a Hockenheim tradition.