Hamilton: Definitely there has been a change in the car

Lewis Hamilton has traced teammate Nico Rosberg's surge in form back to a technical change Mercedes made seven races ago during the Singapore Grand Prix weekend.

Overall, the new triple world champion says 2015 has been the "best year of my career in terms of my driving and overall performance".

Indeed, he dominated Rosberg for most of the season, wrapping up the drivers' title in Austin in September.

But it is German Rosberg who is finishing the season the strongest, with a five-race run of poles and charging for a hat-trick of wins as the calendar concludes in Abu Dhabi.

"People have been asking whether I have subconsciously backed off a little because the championship has been won," Hamilton told the BBC. "Of course you will never know whether that's the case, but it has certainly not been my intention."

And he also plays down the magnitude of his supposed 'slump', insisting that in Mexico and Brazil he had Rosberg's pace in the race but simply couldn't overtake.

But Hamilton does admit that he has felt less comfortable at the wheel since Singapore, where Mercedes famously suffered its famous and mysterious performance slump.

"In terms of my overall performance in the last few races, what I can definitely say is there has been a change in the car," he revealed.

The Briton says no one at Mercedes really knows "what on earth" happened in Singapore, where the team was mysteriously off the pace.

"The engineers looked into it and came up with lots of different explanations and we grabbed at one and changed a few things," said Hamilton.

"But the car had been fantastic all year, so that doesn't really completely make sense to me. And the car balance has not felt the same since.

"It has gone from being underneath me - as racing drivers describe it when they feel confident in what the car will do - to not underneath me.

"The car balance has changed and it has not been as comfortable, while Nico seems to be more comfortable with it," he added.

"I've still got the pace in the race, but it has definitely taken some of my advantage away overall, so now I have to push to try to get the car back to where it was for me."