Anna Kournikova leaves "The Biggest Loser"

Anna Kournikova NBC

(CBS) Anna Kournikova is out at "The Biggest Loser."

The tennis star is leaving NBC's weight loss reality show after spending one season as a trainer.

Kournikova's rep confirmed the news to The Hollywood Reporter on Monday.

"I enjoyed my time on the Biggest Loser ranch. 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 said in a statement.

According to THR, the 30-year-old clashed with staffers and did not sympathize with the overweight contestants. A source told the website that Kournikova was "a nightmare."

Kournikova was hired for Season 12, following Jillian Michaels' departure from the show.

"It wasn't the right fit for her," a "Biggest Loser" source told Us Weekly. "[Her exit] was a mutual decision."