MELBOURNE, Australia, Jan. 21 (Xinhua) -- A disappointed Viktor Troicki retired from his match against Novak Djokovic on Friday, allowing the world No. 3 to move into the fourth round of Australian Open 2011 without breaking a sweat.

The Serbian Troicki retired ill because of a strained stomach muscle after losing the first set 6-2, and called off the match after 39 minutes.

Speaking after the match, the world No. 27 Troicki said that he had first noticed a strain in his second round match against Nicolas Mahut on Wednesday.

"Like any tennis player, you don't wish to win like this," 2008 champion Djokovic told reporters in Melbourne on Friday.

"I knew before the match that he had a little trouble with his stomach. I know it's the third round of a grand slam and he wanted to give 100 percent ... And he was not able."

Djokovic now faces either Nicolas Almagro or Ivan Ljubicic in fourth round in his bid for a second Australian Open crown.