Retired American tennis player Andy Roddick has lifted the lid on his feud with world No 1 Novak Djokovic, revealing the two players almost came to blows in a locker room bust-up.

Djokovic will lose top spot when the new rankings are announced on Monday. Rafa Nadal will return to the top of the men's rankings after Tomas Berdych retired with a back injury during their China Open semifinal on Saturday.

Roddick said he pinned Djokovic up against a locker in the US Open locker room after Djokovic "beat the pants off him" in a match between the two at the final major championship of an ATP tennis season.

Roddick, 31, did not say what year the incident happened but the two had a very public row during the 2008 US Open in New York.

"I won't say his name, I'll just say it rhymes with 'Schmovak Schmokovic'," Roddick said on a panel discussion on the American sports network Fox.

"We got into it at the US Open one time," Roddick said. "I was kind of talking trash and he came out and beat the pants off of me, as he would.

"But then he kind of chirped afterward and he came straight in, I went right up to him and had him up against the locker, but then I realized his trainer was a little bit bigger."

Roddick, who retired in September after the US Open, said he stopped when he realized the confrontation might escalate.

"I kind of checked myself. My trainer is about five-foot-eight, 130 ... I kind of backed off real quick. I was about to get railroaded from the side."

Roddick is a former world No 1-ranked tennis player whose only major championship came at the 2003 US Open.

(China Daily 10/06/2013 page12)