FORT MYERS, Fla. (Kyodo) Boston Red Sox reliever Hideki Okajima went down to the minor leagues Monday for the first time in his career for a reason other than injury.

Okajima will start his fifth year in the United States at Triple-A Pawtucket after posting a 5.14 ERA in seven spring training games.

The Red Sox, finalizing the 25-man roster for the 2011 season, sent Okajima and Alfredo Aceves to Pawtucket while keeping Matt Albers and Dennys Reyes, who did not have options and would have had to be placed on waivers.

"A big part of this decision was the preservation of pitching depth," general manager Theo Epstein said. "It's a numbers game with so many good pitchers pitching well."