Johan Santana is headed under the knife tomorrow.

The Mets lefty returned from a visit to Dr. James Andrews over the weekend that upheld the team’s original diagnosis: Santana has a torn capsule in his left shoulder and needs surgery. That procedure will take place tomorrow at the Hospital for Special Surgery in Manhattan.

Though the Mets are hopeful Santana will be ready for Opening Day next season, there is a strong chance he won’t return until May or June. This will mark the third straight year Santana will have surgery. Last September he underwent surgery to remove bone chips from his left elbow. A year earlier, after the season had concluded, he underwent arthroscopic surgery on his left knee.

The 31-year-old Santana still has not reached the midway point of the six-year deal worth $137.5 million he received from the Mets before the 2008 season.