"The most important thing for me now is to concentrate on getting back to 100 percent fitness," the German said in a team preview on Friday.

"The accident as such does not bother me and I do not have any concerns that I will not be fit for the race next weekend."

Williams, who lead champions Ferrari in the constructors' standings by eight points with three races left, have said that the accident at the fastest circuit on the calendar was caused by a problem with the car's left rear suspension.

Ralf is fourth overall, 14 points behind older brother and world champion Michael who leads Williams' Colombian Juan Pablo Montoya by one point.

The 28-year-old returned to his home in Austria after being kept in a Milan hospital for a night and must rest under medical supervision until Monday.

He told Germany's Bild newspaper that the accident was the worst of his career and he could remember little of the crash after his car flipped.

"It suddenly went bang and it all went dark," he said. "I got myself out and thought 'Ouch, my head really hurts'...In the medical centre I can remember Juan's face and then later in the helicopter I recognised Michael."

Ralf said he loved the Monza track, with its changes between fast and slow sections.

"For this race, my goal is to try to keep my slim chance in the drivers' championship alive," he said. "However it is even more important to perform as a team and to defend our lead in the constructors' championship."