Nico Rosberg says a post-race briefing revealed that a mistake he made deploying KERS helped Lewis Hamilton overtake him in the United States Grand Prix.

Hamilton passed Rosberg under braking for Turn 12 having been a long way back, and admitted he was slightly surprised his team-mate didn’t do more to defend. While Rosberg said he was caught out by Hamilton’s move he also discovered he had not received the help from his KERS that he was expecting which had compromised his chances of defending.

“A little bit [surprised] maybe, yeah,” Rosberg said. “I just found a new thing that I made a mistake because I used the wrong thing to get me more KERS. I thought I was using the right thing but there was a delay in that one.

“If I did it with a button it would be immediate, but with a switch there is a delay, so I never got the extra KERS. So I had a big derate, which is why in the last metres he got a good jump on me. So, that was a mistake that I didn’t know about.

“The last part. I went for extra boost but the way I did it, it only comes on with a delay so I didn’t get extra boost at that particular moment. When I saw him coming I decided to go for extra boost, but I never got it.”

Rosberg also said he may not have changed the way he defended either way, as shutting the door completely on Hamilton could have left him open to another move exiting the corner.

“I am sure I could have done better, but it is a judgement thing. If I defend a lot he will brake late on the outside and get me on the next one, so I thought indicating I am closing the door would have been enough to stop him from trying, but it wasn’t. Because I was part way over already and I thought that was enough for him to think he should not try, but it wasn’t.”