By STEPHEN WILSON - AP Sports Writer

LONDON(AP) Floyd Landis' stunning Tour de France victory just four days earlier was thrown into question Thursday when his team said he tested positive for high levels of testosterone during the race.

The Phonak team suspended Landis, pending results of the backup "B" sample of his drug test. If Landis is found guilty of doping, he could be stripped of the Tour title, and Spain's Oscar Pereiro would become champion.

It wasn't immediately known when the backup sample will be tested.

The Swiss-based Phonak team said it was notified by the International Cycling Union (UCI) on Wednesday that Landis' sample showed "an unusual level of testosterone/epitestosterone" when he was tested after stage 17 of the race last Thursday.

"The team management and the rider were both totally surprised of this physiological result," the Phonak statement said.

Efforts to reach Landis were not immediately successful.

The 30-year-old Landis made a remarkable comeback in that Alpine stage, racing far ahead of the field for a solo win that moved him from 11th to third in the overall standings. He regained the leader's yellow jersey two days later.

Landis rode the Tour with a degenerative hip condition that he has said will require surgery in the coming weeks or months.

Arlene Landis, his mother, said Thursday that she wouldn't blame her son if he was taking medication to treat the pain in his injured hip, but "if it's something worse than that, then he doesn't deserve to win."

"I didn't talk to him since that hit the fan, but I'm keeping things even keel until I know what the facts are," she told The Associated Press in a phone interview from her home in Farmersville, Pennsylvania. "I know that this is a temptation to every rider but I'm not going to jump to conclusions … It disappoints me."

The Phonak statement came a day after the UCI, cycling's world governing body, said an unidentified rider had failed a drug test during the Tour.

Phonak said Landis would ask for an analysis of his backup sample "to prove either that this result is coming from a natural process or that this is resulting from a mistake."

Phonak said Landis has been suspended and that he will be fired if the second sample confirms the initial finding.

USA Cycling spokesman Andy Lee said that organization could not comment on Landis.