TORINO, Italy -- Nine-time United States champion figure skater Michelle Kwan has withdrawn from the Winter Olympics because of a groin injury.

Kwan, who did not take part in the U.S. Figure Skating Championships last month because she was hurt, suffered an unrelated injury at practice Saturday morning and the problem worsened during the evening.

"Taking myself off the team is the most difficult decision I've ever had to make," Kwan said in a release from the United States Olympic Committee, "but it's the right decision. This injury prevents me from skating my best, and I've said all along that if I couldn't skate to the level that I expected from myself I'd withdraw from the team."

Kwan apparently hurt her right hip adductor while trying to land a triple flip jump during Saturday's workout.

"The Olympics is the greatest sporting event in the world and what's most important is that the United States fields the strongest team possible. As much as I'd love to represent the United States in Torino, I would never stand in the way of that," she added.

Kwan was set to appear in her third Olympics. She won a silver medal in 1998 and a bronze in 2002.

Emily Hughes, sister of 2002 gold medal winner Sarah, will take Kwan's spot on the team.

Kwan said Saturday she cut her practice short because of "stiffness," adding that participating in the Opening Ceremony and standing in the cold for some four hours did not do her body any good.

Apparently there was more to it than that.

According to the USOC, Kwan's pain worsened as the day went along and she was evaluated early Sunday morning in the athletes' village by U.S. team physician Dr. Jim Moeller, who diagnosed the five-time world champion with a severe groin strain.

"This injury limits her function, making it impossible for her to jump, land and skate effectively and without risk of serious injury," Moeller said in the USOC release.

Moeller added that, in his opinion, the latest injury was unrelated to prior problems.

After skipping nationals, Kwan had to prove to a special committee that she was fit to earn a spot on the United States team. She did that late last month and was granted a berth in place of Hughes, the third-place finisher at the U.S. Figure Skating Championships.

At Saturday's press conference, Kwan, an alternate for the 1994 Games in Lillehammer, was asked what advice she would give Hughes.

"Be prepared," Kwan said.