Nico Rosberg does not believe there is a specific reason why he has been able to beat Mercedes team-mate Lewis Hamilton at recent races, arguing he simply has the "upper hand" at the moment.

Hamilton secured this year's title at the U.S. Grand Prix after dominating for much of the season, but Rosberg has hit back at recent races. He has won the last two grands prix and taken pole position at the last five, leading to questions over what has changed between the Mercedes drivers.

Hamilton alluded to changes to the car after the team's struggles in Singapore as the reason, but Rosberg denies that was a factor in the way it handles.

"I'm not really sure what he [Hamilton] is referring to, but there is no change in the feel of the car or anything," Hamilton said. "For me it was always very close before and now it's just swung the other way. It's very close but I'm ahead now and I'm quicker and that's it.

"Last year I was quicker in qualifying and the beginning of this year I was not and now I am again, so it's just been toing and froing a little bit and at the moment I'm the one with the upper hand."

Rosberg said there are areas on the car he is hoping to change for next year, but other than his ongoing struggles with the car's brakes, doubts there is much that will help him more than Hamilton.

"There are always some small bits and pieces where I'm trying to get them to change some stuff, which I feel could be beneficial. But more often than not it's also helpful for the other guy, it's seldom that something will just help me and not Lewis, but of course there are things I am trying to push for, yes. But some things take so long, like brakes, which has been since the beginning of last year and it just takes so long and it's not straightforward."