By Sportswriter Fei Liena

    BEIJING, Aug. 17 (Xinhua) -- Two boxing world champions were kept out of the top four Sunday night at the ongoing Beijing Olympics.

    At the first match of the day, twice world champion, Kazakhstan's light welterweight (64kg) Serik Sapiyev witnessed his bitter defeat 5-7 by Athens Olympic champion, Thai Manus Boonjumnong.

    Not as strong as Sapiyev, the Thai cleverly took advantage of his fast pace to avoid heavy punches, and tried to hit as many effective points as possible.

    Another world champion, U.S. welterweight (69kg) Demetrius Andrade also suffered a stunning defeat by another Asian, South Korean Kim Jungjoo by a controversial score of 9-11.

    The two tied each other throughout the fight, with the tall and strong Andrade throwing punches all the time, and the much smaller Kim relying on his quick footwork and sudden attacks to score.

    Unsatisfied with the judges' scoring, the American left the ring in outrage before the referee announced the winner.

    "(I tried to) Throw twenty punches. Throw whatever I can," Andrade said:" I was landing them but I didn't get the score."

    He didn't think he lost at all. "I fought my heart out but sometimes life is unfair," he said.

    Luckily the Chinese welterweight boxer Hanati Silamu didn't have to feel the agony today. He smashed his Bahamian opponent Toureano Johnson by a convincing 14-4, making way to the last four of his category and guaranteed at least a bronze medal at the Olympics.

    The two rivals pulled themselves all out to attack immediately after the bout began. For being both aggressive and strong, the Chinese possessed a more steady defence and so slightly led the race. In the last round, things turned dramatic. The Bahamian, obviously burnt out all his energy at former rounds, appeared incapable of throwing powerful punches and standing the vicious attacks from Silamu. After taking two standing counts by the referee, Johnson was declared defeat.

    With this victory, the Chinese strode into the last four family and has secured at least a bronze medal.

    The Cubans continued to dominate the ring on Sunday, with all their three master-hands crushing their respective challengers, including world championship runner-up Russian Gennady Kovalev.

    To ease some pain of the Russians, another world championship runner-up of theirs, Rakhim Chakhkiev, vanquished French John Mbumba, third of last year's world championships with a big lead.

    Heavyweight world champion Italian Clemente Russo presented a cunning fight with some tricks, obviously irritated his opponent Ukrainian Oleksandr Usyk. Yet Russo did get an easy 7-4 victory.