In September 2000, Sakai was selected the Japan U-23 national team for 2000 Summer Olympics who carried high hopes of the nation because Sakai's teammates included such household names as Hidetoshi Nakata, Shunsuke Nakamura and Naohiro Takahara. Sakai played all 4 matches. However, in the team's quarterfinal match, Sakai committed a foul inside his own box at the 90th minute, conceding the United States, Japan's opponents, a crucial penalty to make it 2-2. The United States went on to win the penalty shootouts after 120 minutes of play could not separate the two teams.