Manny Banuelos, considered the New York Yankees' top pitching prospect, is scheduled to undergo Tommy John surgery Thursday that likely will sideline him for the 2013 season. Dr. James Andrews will perform the procedure in Pensacola, Fla., on the 21-year-old Banuelos, who hasn't pitched since May for Triple-A Scranton/Wilkes-Barre. The Yankees apparently thought the injury was a bone bruise and had hoped surgery wouldn't be needed. The left-hander started a combined 27 games last season for Double-A Trenton and Triple-A Scranton/Wilkes-Barre, posting a 6-7 record with a 3.75 ERA and 125 strikeouts in 129 2/3 innings. In five minor-league seasons since he signed as an international free agent in 2008, Banuelos is 19-19 with a 3.12 ERA with 375 strikeouts and 147 walks.