Seranthony Dominguez was already slated to miss this season, but his wait to undergo Tommy John surgery could cost him the 2021 season as well.

Dominguez injured his right ulnar collateral ligament in June 2019 but was told by renowned orthopedist James Andrews that surgery was not required. The right-handed reliever missed the rest of last season, followed a throwing program, and was expected to be a part of the bullpen this season.

But Dominguez felt discomfort in March during spring training and again visited Andrews, who recommended surgery. But spring training was canceled soon after, and the season was delayed. Dominguez returned to the Dominican Republic as the borders were being closed, and it would have been difficult for him to have an elective surgery during the early stages of the pandemic.

Dominguez returned to the United States in June to undergo the surgery, but he has yet to have it.

“We are hopeful that will happen soon,” general manager Matt Klentak said Thursday. “And the reason that it’s been further delayed is a reason that I can’t really talk about it. He’s doing fine. He’s healthy. He’s preparing for that surgery. I expect it will happen soon. But I can’t get into why it didn’t happen in the last few weeks.”

If Dominguez has surgery soon, the best-case scenario would have him returning to the team in August 2021. But there’s also the likelihood that his rehab process will require more time. To pitch next season, Dominguez would need to return after a 12- to 14-month rehab. That could be a challenge.

Dominguez, 25, was expected to play a key role in a bullpen that did not get much upgrading in the offseason. He was electric as a rookie in 2018 and averaged 11.2 strikeouts per nine innings over his first 80 major-league appearances.

Instead, the Phillies will begin a 60-game season on Friday with 11 other relievers in their bullpen and cross their fingers that Dominguez can contribute next year.