Singapore GP: Nico Rosberg surprised to be so close to pole

The German came closest to toppling the current championship leader towards the end of the session, but was 0.091 seconds shy of beating his compatriot.

When asked as to how he was able to produce such a performance, Rosbeg said: "It's very difficult to explain and I don't know.

"I didn't expect such an improvement, maybe track ramping up or cooling down, I am not sure."

He is optimistic he can challenge Vettel in Sunday's race on a circuit that he has excelled on in the past.

"I really like street tracks and I always go quick on them, so second place is still a good result and gives me a good position to attack tomorrow," said Rosberg.

"If I can get by Sebastian, and the left-hand side has less grip than the right, then anything is possible."

Team-mate Lewis Hamilton qualified fifth for the race, a major improvement on his 12th on the Italian Grand Prix grid, but the Briton remained downcast.

"I just wasn't fast enough today," admitted Hamilton.

"But clearly the car was quicker than I was able to get out of it. I will just have to do my best tomorrow."