Nico Rosberg admitted it would have been hard to beat Sebastian Vettel to pole ahead of the Brazilian Grand after qualifying second behind his countryman at Interlagos.

In challenging conditions in Sao Paulo, Rosberg put his Mercedes on the front row for the seventh this time season, but was more than six-tenths of a second down on Vettel's Red Bull.

Blaming a lack of KERS in the final sector for some of the gap to Vettel ahead, Rosberg said he was pleased with the result even if he was surprised to be so far behind the four-time champion.

"That was a very demanding qualifying session today with really tricky conditions and a long break before the final session," he said. "I'm really pleased to have achieved second place on the grid and a big thank you to the team for their work; we did everything right today.

"My target was to give Sebastian a hard time so I was surprised that the gap was so big in these conditions. I lost time in the last sector compared to him which was down to a lack of KERS power when you do two consecutive quick laps. However, it would have been hard to beat him even if we'd had a perfect lap.

"Being on the front row gives us a great opportunity in the race but the most important thing is to stay in front of the Ferraris."