Michael Schumacher admitted he was at a loss to explain his struggles during qualifying for the Canadian Grand Prix.
The German finished down in 13th position after being unable to make it to Q3, the seven-time champion unhappy with his car's handling. It was the first time that Schumacher has been outqualified by a teammate in Canada.
He said he found it hard to understand the reasons for his problems.
"I am obviously disappointed after today's qualifying," said Schumacher. "We simply did not have the balance or grip and overall we had a lot of problems with braking and handling. The car was just not performing as we expected.
"We had similar issues yesterday afternoon and we made some changes after second practice. This morning, the changes seemed to have made sense as our position was reasonable but this afternoon, I was facing similar issues again. It's difficult to understand the reasons at the moment, but we will look deeply into it now and find a good strategy for the race tomorrow."
Mercedes teammate Nico Rosberg completed a disappointing day for the German squad after finishing as 10th quickest.
"That wasn't a great qualifying session for us today," he said. "We have a good car here this weekend but unfortunately we couldn't get the tires to work properly this afternoon. That was the big issue for us today. The harder tire wasn't too bad in Q1, but we struggled with the option later on and there was just no more lap time to be had.
"It is very disappointing to be starting in 10th place, but anything can happen in the race so we can only look forward and take advantage where possible tomorrow."