Tazawa's surgery will be performed by renowned orthopedist Dr. James Andrews, who examined the Japanese right-hander earlier this week.
Countless pitchers have made full recoveries from Tommy John surgery, and the Red Sox expect the same will happen for Tazawa, who is 23 years old.
When will Tazawa return to the mound?
"Typical Tommy John timeline," said Red Sox general manager Theo Epstein. "You're looking at 10 to 12 months, but we're usually a little conservative. There's a chance he could have a Spring Training next year and pitch [early] next season."
Boston scouted Tazawa in Japan's industrial league and signed him to a three-year Major League contract on Dec. 3, 2008. He was promoted to the Red Sox in August of last season, going 2-3 with a 7.46 ERA in six games, four of which were starts. Tazawa fired six shutout innings against the Yankees on Aug. 22. He spent most of 2009 at Double-A Portland, going 9-5 with a 2.57 ERA in 18 starts. Tazawa pitched twice for Triple-A Pawtucket before his promotion to the big leagues, notching a 2.38 ERA in two starts.
Both Tazawa and the club had known for the past couple of days that Tommy John surgery, in which a ligament is transferred from another part of the body to the elbow, was likely.
The righty will return to Fort Myers after his surgery and began his rehab there.