The Strictly Come Dancing partner of contestant Joe Calzaghe says he needs to lose weight to stand a chance of winning the show.

Not light on his feet: Joe Calzaghe and Kristina

Professional ballroom dancer Kristina Rihanoff, 31, has put the former boxer, the undefeated world super middleweight champion, on a strict diet, she said last night.

“Joe has put on two stone recently,” Kristina said during a party at Soho's Sanctum Hotel.

“He's a little big at the moment to win, but he is on a strict diet. He really wants to win, but he needs to lose the weight if he's to stand a chance.”

The Russian dancer also had a slight dig at John Sergeant, her partner from last year's show, who was labelled a “dancing pig”. She said: “It's nice to have someone fitter and more focused.”

Only weeks ago Calzaghe, 37, declared that if he ever turned up on a reality TV show “you can shoot me in the head”.

But he changed his mind and signed up to the hit BBC show, making him 5-1 favourite to win at Ladbrokes.

But off-screen Calzaghe is pre-occupied after splitting from his girlfriend, 28-year-old Jo-Emma Larvin. The couple reportedly decided to call time on their relationship after a series of rows. They started dating five years ago, after the father of two separated from his wife, Mandy.