Anna Kournikova won't return to 'Loser'

Tennis star Anna Kournikova won't be back as a trainer on "The Biggest Loser."

The Moscow-born Kournikova, 30 -- who never rose above No. 8 in women's rankings but who has graced the covers of the Sports Illustrated swimsuit issue, Maxim and other magazines -- had proved an uncomfortable fit on the show, said the Hollywood Reporter. Staffers of the NBC show told the Reporter that she clashed with them and was brash with the contestants, highly overweight individuals competing to shed pounds through exercise and diet. She could be unsympathetic with them, the staffers said, as opposed to tough-but-inspirational longtime trainer Jillian Michaels, whom Kournikova had replaced.

"I enjoyed my time on 'The Biggest Loser' ranch," Kournikova told the Hollywood Reporter. "Although I will not be returning as a full-time trainer on season 13, I will always be a part of 'The Biggest Loser' family and my commitment to bettering lives through health and fitness will continue."

At least one contestant has lauded Kournikova. Recently eliminated Joe Mitchell, 46, said he was grateful that she was able to "fix my thinking." He told People magazine over the weekend, "Anna made me believe that I could [lose weight]," he said. "She drilled in our heads that the only person you can really rely on is yourself."