Sir Frank unconcerned by criticism over Button

Button, who is being replaced at Williams-BMW by Champ Car ace Juan Pablo Montoya, has been widely praised for an impressive debut season - not least from Williams himself. But the eponymous team boss has faced flak from the media and within the sport itself for loaning the rookie to Benetton.

"Yep, I know people are saying that," Williams told Autosport magazine, "and maybe they'll turn out to be right. Others are saying we're getting rid of the wrong bloke - that we should be keeping Jenson, instead of Ralf [Schumacher] - but only time will tell.

"Whatever happens, I won't lose any sleep over it. It was only nine months ago after all, that those same people were saying it was a mistake to put a young child in the car."

This year's Williams has proved to be a better car than the FW21 of last season, but Schumacher scored fewer points this year with Button as team mate than in 1999. Insiders within the team suggest Schumacher has become fazed on days when Button has been very quick.

Williams says the German will need to have his wits about him when Montoya joins the team.

"Ralf has had a few more bad days than he ought to have had [this year]," he said. "He'll just have to get his head together. In the races he rarely disappoints, but perhaps his mind control has not kept up with the progress in his career. We'll see."

Button, Montoya and Schumacher all take to the track together for the first time when winter testing begins next month. Button will get his first run in an interim Benetton on December 4 and the new Williams pairing will be on hand the following day.