Fernando Alonso was penalized five spots on the starting grid for Sunday's Italian Grand Prix.
Race stewards judged that the defending Formula One champion impeded Ferrari driver Felipe Massa at the end of Saturday's qualifying.
Alonso was dropped from fifth to 10th position.
The penalty is a big blow for Alonso and his Renault team, which are facing challenges for their leads in both the drivers' and constructors' standings. Alonso holds a 12-point lead on Michael Schumacher in the drivers' standings and Renault leads Ferrari by two points in the team standings.
Schumacher will start Sunday's race in second position and Massa in fourth, reports AP.
"I didn't block anyone," Alonso said before the penalty was decided. "He was 300-400 meters behind me. I did my best sector times in the outlap. So it's a strange complaint."
Massa felt he could have posted a top-two time.
"It's a shame, because I felt capable of putting (the car) on the front row," Massa said.
Stewards ordered that the best three laps set by Alonso in the final period of qualifying be deleted. His initial time of 1 minute, 21.747 seconds was replaced with 1:25.688.