TOKYO -- Pitcher Koji Uehara, whose dominant season in relief helped the Boston Red Sox win the 2013 World Series, has retired with Japan's Yomiuri Giants -- the team that he first played for in Japan.

The 44-year-old Uehara announced his retirement at a news conference in Tokyo, saying it was time to step away after he was unable to perform well early in the season for the Giants' farm team.

Uehara joined the Baltimore Orioles in 2009, but he became a star in 2013 with the Boston Red Sox, who defeated the St. Louis Cardinals that year in the World Series. He was dominant in relief that season for the Red Sox and it was Uehara who threw the last pitch in the final game when Boston beat the Cardinals 6-1 to win the World Series.

Uehara was 22-26 in his nine-year career in MLB and pitched his final season in 2017 with the Chicago Cubs. He also pitched for the Texas Rangers.

Uehara started with the Yomiuri Giants in 1999 and pitched for 10 seasons in Japan before moving to MLB.