HOCKENHEIM, Germany -- Michael Schumacher crashed near the end of a wet second practice for the German Grand Prix and was unhurt as he walked from his damaged Mercedes on Friday.
Pastor Maldonado of Venezuela, winner of the Spanish GP, ended with the fastest time in his Williams, with the order decided largely by who was on the track when it was driest.
Schumacher, in the third and possibly last season of his comeback, lost control on bend 12, spun out and hit the tire barrier, ripping off the rear of his car and damaging the left side.
"I simply slid off track because I lost a little concentration: we were talking on the radio and I was altering some settings at the same time," Schumacher said.
He got up and walked away, before returning to watch the marshals haul the wreck away.
The crash brought out the red flag, ending the session with less than four minutes remaining.
Schumacher has won the German GP a record four times and was the last German driver to win his home race, in 2006, his last season with Ferrari. Mercedes is seeking its first win on home soil since 1954.
"The way I ended the second session was obviously not part of the plan and I'm sorry that my mistake has given my guys even more work to do this evening. I think that qualifying will probably be wet tomorrow, so today's weather was useful in that respect," the 43-year-old veteran said.
Heavy showers drenched the afternoon session that produced times more than 10 seconds slower than the first morning practice that was hit by occasional rain.
With light rain hitting the circuit on and off, Button set the pace with a lap of 1 minute, 16.595 seconds, edging Hamilton by .498 seconds. Maldonado's best lap, by comparison, was 1:27.476.
Hamilton will be driving his 100th grand prix on Sunday.
Championship leader Fernando Alonso of Ferrari was third in the morning, ahead of Schumacher.
In the afternoon, Schumacher was next-to last in 23rd, while Alonso was 20th.
Mark Webber of Australia, second in the drivers' standings, was 20th in the morning and ninth in the afternoon in his Red Bull.
Two-time defending champion Sebastian Vettel, who has yet to win a home race, was third in the afternoon in the second Red Bull, after finishing 12th in the morning.
"We couldn't learn too much today, so we just got used to the conditions, as there may be rain tomorrow and also on Sunday. The forecast isn't looking great," Vettel said. "It would have been good to have got some dry running in, especially this afternoon to test a couple of things and see how the car feels."