Sebastian Vettel is worried about the performance of his Renault engine ahead of the Italian Grand Prix.
The young German was between 2 and 3 kph slower than his teammate Mark Webber in a straight line on Saturday; a handicap described by the Australian as "peanuts".
But Vettel, having qualified at Monza lower than ever in 2010, said: "Overtaking is going to be very difficult."
Team consultant Helmut Marko told Bild newspaper: "We do not have a super engine."
Vettel's extra speed deficit at Monza is a mystery.
"It was a new engine," Vettel confirmed, "but it seems not to be as good as we expected."
He is not sure what he is expecting from the Monza race.
"It's hard to tell -- better than sixth place, I hope," said the German. "And it's better that it is Fernando and not Lewis on pole position."
He vowed to take a normal approach to the start of the race.
"I'm not sure; either I act like a bowling ball and knock everyone out of the way as all the experts expect me to do now, or I will approach the race as usual," he answered sarcastically.