Seattle Mariners third baseman Adrian Beltre will undergo surgery to have bone spurs removed from his troublesome left shoulder.

Beltre's non-throwing shoulder was operated on in September for the same reason and has given him severe pain all season. The two-time Gold Glove winner made his decision before Saturday night's game against the Dodgers, and he could be sidelined for four to six weeks.

Beltre, who also had surgery on his left thumb in September, entered Saturday batting .260 with five homers and 30 RBIs. The 12-year veteran, who becomes a free agent after this season, was in the starting lineup Saturday night and flied out to the warning track in center field his first time up.

Beltre established career highs in 2004 with a .334 average, 121 RBIs and a major league-leading 48 homers for the Dodgers despite playing the entire season with bone spurs in his left ankle. The home run total tied Mike Schmidt's 1980 record for third baseman. He signed a five-year, $64 million with Seattle a few months later.

Beltre was held out of last Sunday's 9-3 victory by manager Don Wakamatsu, and X-rays on Tuesday confirmed that the bone spurs were back. He was hitting .336 over his previous 29 games after ending an 0 for 23 drought. He was 0 for 4 in Seattle's 8-2 loss on Friday night.