Kournikova leaving 'Biggest Loser'

Anna Kournikova is leaving "The Biggest Loser" after serving as the head trainer for the weight-loss reality competition for just one season, The Hollywood Reporter said Monday.

"I enjoyed my time on 'The Biggest Loser,'" the Russian tennis star said in a statement.

"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," she added.

Kournikova, 30, said in May she couldn't "wait to get started on the show" to replace trainer Jillian Michaels.

But sources close to the NBC show said Kournikova was "a nightmare" to work with and others complained she was unsympathetic to contestants that struggled with the athletic exercises in their quest to lose weight.

Season 12 of the series started Sept. 20 and will end in mid December.