Washed up Coulthard thinks Schu is washed up too

David Coulthard says time is running out for Michael Schumacher to prove to everyone that he still has what it takes to compete at the top in Formula One.

The seven-times World Champion endured a shocking Canadian Grand Prix. He was involved with separate clashes with Robert Kubica, Felipe Massa and Tonio Liuzzi and he hardly managed to put up a fight when he was overtaken by Toro Rosso's Sebastian Buemi and both Force Indias.

BBC commentator Martin Brundle slammed Schumacher after the race saying he drove "appallingly today" and described his performance as his "worst weekend since he came back".

Writing in his weekly Telegraph column, Coulthard says Schumacher "resorted to some pretty questionable racing" in Montreal and also warns that he only has few more races to convince people that his return wasn't a mistake.

"He has won a record seven times on the Ile Notre-Dame but in all honesty he looked a shadow of his former self on Sunday," Coulthard wrote.

"He pitted three times and was still lapping over 4 seconds off the pace in his final stint. He just could not get his tires working and in my view resorted to some pretty questionable racing in an effort to hold position. He was particularly fortunate to escape sanction for the late collision with Massa, his old protégé at Ferrari. The rules are clear: you cannot make two moves under braking. I'm not sure why they let him off.

"I'm not beating up on Michael. We have had our differences in the past but I have tremendous respect for him. And I have consistently said we need to give him half a season before we judge his comeback. But with eight races gone and 11 to go, we are getting dangerously close to that tipping point.

"What is wrong with him? I don't know but something is clearly missing. It seems a case of one step forward, two steps backwards at the moment. I don't think the reactions have gone, his fitness is fine and to be fair to him he has shown glimpses of his old race craft; the move on Alonso on the final lap in Monaco was like a visitation from the ghost of Schumi past."