Austin: Nico Rosberg accused newly-crowned world champion Lewis Hamilton of being "extremely aggressive" and "going one step too far" at the start of Sunday's United States Grand Prix.
The disappointed German finished second behind his Mercedes team-mate after starting from pole position and blamed himself for losing the race with an unforced error late in the race.
But, he added, Hamilton's aggression at Turn One was "too much and one step too far" and said it was not acceptable.
"He was extremely aggressive at the start. We hit each other. Or should I say Lewis came into me, which is not good."
Speaking immediately after the race, he said he had not seen a video re-run of the start and was reluctant to comment, but later he was adamant that the move was too aggressive to be acceptable.
But he made the point that he recovered from that setback on the first lap and could only blame himself for failing to win in the final laps after running wide on the 49th which opened the door for the Briton to seal a third world title
"It was my mistake that cost me the race and it was for me a very tough moment and so strange -- it has never happened to me before, not even in free practice, not in the whole season," added Rosberg.
"I just spun off on my own -- maybe the tyres were a bit cold. It is very disappointing because the race was mine.
"I am not saying anything was wrong with the car. I am assuming it was a mistake I made."
Rosberg later added his congratulations to Hamilton.
"He deserves the championship. He has driven very well all year and he has been consistent and it is well deserved." However, there was still an undercurrent of the bad feeling between the two drivers in the crew room just after the race.
Hamilton tossed the German a cap to wear on the podium but 30-year-old Rosberg immediately threw the hat back at the stunned Briton.