Jenson Button has blamed poor visibility with the new 2017-specification cars for his collision with Sauber's Pascal Wehrlein.
Making his last start in Formula 1, Button was running at the back of the field after gambling on an early safety car that didn't materialise.
He was running behind Wehrlein on lap 60 when he tried a move down the inside of Portier just before the tunnel entrance. The two collided, with Wehrlein left upended against the barrier. Button himself retired with broken left front suspension.
“I went up the inside, and I thought it was on," said Button of his attempt to pass Wehrlein. "Otherwise I wouldn't have made the move.
"I got alongside - well, from where I was I thought I was alongside him - but then I looked across. I thought, 'He hasn't seen me at all'.
"These cars are so difficult to see out of the back of," he explained. "I've been telling the team and the FIA that this weekend.
"I tried to back out of it, but it was too late and we touched," he added.
"I've never seen a car go up on its side before. I don't know if that's the way the tyre is or if that's just unlucky today. Horrible to see."
Wehrlein escaped without obvious injury. However he will need further scans to check that he hasn't exacerbated the back injury he sustained at the Race of Champions in January.