BEIJING, Aug. 9 (Xinhua) -- Ivo Karlovic and Ivan Ljubicic, both are Croatia's tennis medal hopefuls, withdrew from the Beijing Olympic Games on Saturday.

    Karlovic, the 14th seed who withdrew from the Games because of a stomach illness, is replaced by China 's Yu Xinyuan who faces Tomas Berdych of the Czech Republic in the first round.

    Ivan Ljubicic also pulled out of singles due to back trouble. He still plans to play doubles in the tournament, which begins Sunday.

     Ljubicic, who won a bronze medal in the doubles four years ago, was replaced by Devin Mullings of the Bahamas .