Brazilian GP: Sauber changes 'many parts' to try to help Wehrlein

Wehrlein believes something has been wrong with his car as he has been forced to go in a different direction to team-mate Marcus Ericsson, having been "very close" on set-up all season.

Ericsson has outqualified Wehrlein in the last three grands prix and Sauber has opted to introduce newly-made parts to the same specification in a bid to solve Wehrlein's problem.

"We changed many parts on my car because I was struggling in the last few races," said Wehrlein.

"We hope that we can fix the issue. I'm just struggling with the balance of the car.

"The two cars behave very differently. In some high-speed corners I'm losing so much, and struggling a lot with oversteer.

"For me it seems like there's something going on at the rear of the car. It's since Malaysia.

"Malaysia was a very strong race, I was close to Q2, I was very happy with the performance there. But then after that it was different.

"Marcus and me have always been very close in terms of set-up the whole season, and now we just need to set-up the car completely different, which is a bit strange.

"We changed the floor in the last race, and now we're changing some more aero parts on the back. We also have new suspension for this weekend."

Wehrlein revealed he had requested a change of chassis but it was not a viable option.

"I would have liked to have changed the chassis for this weekend, but unfortunately we couldn't," he said.

"We have one that is very old, and the other one had to be repaired twice because of Antonio [Giovinazzi, crashing in China] at the beginning of the season.

"This one, we don't want to use."

Wehrlein enjoyed one of his best races of 2016 at Interlagos, finishing 15th for Manor after running in the points until the second half of the grand prix.

"I hope for a similar race to last year," he said. "It was a very exciting race, and I was driving for quite a long time in the points.

"But I heard on Sunday it should be dry, so let's see."