Nick Heidfeld says his late slump in the Chinese Grand Prix was due to damage sustained when he collected debris from Adrian Sutil's heavy accident.
The Force India spun into the barriers with five laps to go and sustained severe front-end damage, with a detached wheel hitting Heidfeld's BMW, which was running eighth at the time but subsequently slipped to 12th.
"Close to the end of the race I had the chance to score one or two points, but then there was a lot of debris on the track, including a wheel, from Adrian Sutil's accident," said Heidfeld.
"I tried to find a way around it, but it was unpredictable which way it would go and it hit me. Afterwards the car felt very strange and I lost four places."
He said he had already been struggling with damage from an earlier tangle with Timo Glock.
"On lap 13 Timo Glock hit me, which caused damage to the car and certainly didn't help," Heidfeld said.
"Of course I'm disappointed with the outcome of today's race, but at the same time I feel I should be grateful I was able to finish it at all."