Italian GP: Rosberg engine problem 'big question mark' for Mercedes

Rosberg's qualifying session was compromised when he had to revert to the previous specification of engine after free practice, and he could only qualify fourth on the grid at Monza.

Mercedes is yet to discover the cause of the problem, and Wolff added it is still trying to work out if Hamilton could be affected too.

"We simply don't know what the root cause of the problem was on Nico's engine, but we don't think it was performance related," said Wolff.

"In terms of Lewis's engine, there is still a big question mark about what's actually happened and the potential risks for Lewis.

"If we find out that it is a major issue and is something that would put Lewis's race at risk [an engine change] is certainly something we would consider.

"Our car has great pace, and it would be better to play it safe."

Wolff sympathised with Rosberg, who he believes was hindered by the last-minute engine change.

"The combination of an old engine and a car which wasn't set up to these conditions made Nico end up in P4," he said.

"If you take the engine out of the car just before qualifying that puts you in a situation that is more difficult mentally.

"At the moment we don't know what the issue is but I still have every belief it is something we can solve."

Rosberg praised his mechanics for the speedy engine change but insisted the move to an older unit will hamper his whole weekend.

"We realised [there was a problem] directly after FP3," he said.

"The mechanics did an incredible job on my car to change everything in one and a half hours which was great and fantastic.

"It has a lot of mileage, it has done six races, and engines degrade over time.

"It has definitely compromised my weekend and will compromise my race as well."

When asked if he was confident he could beat Ferrari's Kimi Raikkonen and Sebastian Vettel, who start second and third, on Sunday, he said: "Ferrari for sure. Lewis [will be] more difficult.

"I'm seven hundredths away [from Ferrari] in qualifying and I think in the race they will not have the same modes they had in qualifying so I have a good chance."