Anna Kournikova has made her debut as a personal fitness trainer in 'The Biggest Loser'.

The tennis star - who previously appeared as a special guest on the series, which features obese people attempting to lose the highest percentage of weight relative to their original size to win a cash prize - started her job on the season 12 premiere of the NBC show on Tuesday (20.09.11).

Speaking on 'Live with Regis & Kelly' about how her mum is to thank for her fitness work, the 30-year-old beauty said: "She really instilled the commitment, disciplinary In Me. It's really helped me throughout life and that's why I'm so passionate about sports and fitness and promoting that healthy lifestyle, and spreading the word especially to kids."

Anna - who was once ranked as the eighth best female tennis player in the world - explained her sports background has played a part in helping her prepare for the role.

She added: "You can learn so much through sports. It teaches you all these amazing skills you can use in life, not just while you're playing sports."