MONTREAL (AP) The track curved 180 degrees to the right but Lewis Hamilton's Mercedes kept going straight, skidding slowly into the safety barrier.
After posting the fastest time of the opening practice and again early in the afternoon session, Hamilton was done for the day. And with the rain turning into a torrent, so was everyone else.
''It didn't quite end the way we wanted it too,'' Mercedes technical chief Paddy Lowe said Friday after the storm caught his team out on the track and left the leader in the championship standings with a damaged car.
''Unfortunately, the conditions worsened faster than we anticipated,'' Lowe said. ''We'll get it sorted out for (Saturday). It should be all fine.''
Hamilton posted the fastest lap in the morning practice, completing the 2.71-mile (4.361-km) Circuit Gilles Villeneuve in 1 minute, 16.212 seconds. He ran the course in the afternoon in 1:15.988 before the rain cut the 90-minute session in half.
''The ending might have been so-so, but it's generally been a pretty good day,'' Hamilton said. ''I made a couple of mistakes - pushing too hard and going over the curbs at the final chicane and then what happened at the end there.''
Mercedes teammate Nico Rosberg was second in the first practice, followed by Romain Grosjean of Lotus and Nico Hulkenberg of Force India. In the afternoon, the Ferrari teammates of Sebastien Vettel and Kimi Raikkonen were second and third.
Practice continues Saturday morning before qualifying in the afternoon. Hamilton has won the pole position in five of the first six races this season.
Hamilton had a harmless spin in the morning session and caught some air when he went over a curb on the dry track early in session two. As the rain picked up, only Mercedes was still running and Hamilton hydroplaned as he tried to navigate the hairpin turn.
The driver quickly signaled that he was OK, and he walked away without any apparent injury. His car wasn't so lucky, with the nose wedged into the barrier. More damage was done when the crane had to yank it out.
Hamilton said he wasn't going too fast ''but it was like sheet ice'' heading into the hairpin.
''It maybe wasn't the right call to go out but, with the weather as it eventually turned out,'' he said. ''(But) it didn't affect our running. I'm fine, and it looks like it's just the front wing that was damaged to it's not the end of the world.''
But that's not the only damage control for Mercedes this weekend.
Hamilton was leading in Monaco two weeks ago when a late crash brought out the safety car, and Mercedes called him in to change tires. Rosberg and Vettel passed him, and it was too late for Hamilton to retake the lead; instead of his fourth victory of the season, he finished third.
Hamilton was visibly angry after the race, but he insisted after arriving in Montreal that he had full confidence in his team. A three-time winner in Montreal and a two-time Formula One world champion, he still holds a 10-point lead over Rosberg in the standings.
Lowe apologized to Hamilton after the race, and on Friday walked back some comments in which he seemed to downplay the importance of what he said was a software mistake.
''Of course it was a big deal,'' Lowe said, adding that he just ''wanted to stand up for my guys that make very few errors. Formula One is complex, a lot of things to get right. Most of the time, we do that.''