NEW YORK -- The New York Yankees have lost another important player to injury. In this case, it's a player who returned from a season-long shoulder problem just this past weekend. Following Tuesday's win over the Angels (NYY 8, LAA 0), the Yankees announced reliever Dellin Betances has suffered a partially torn left Achilles tendon. 

He will receive a second opinion soon but surgery has not yet been recommended. Either way, the season is over for Betances.

"Just sad," Luis Severino, who returned from his own season-long shoulder injury Tuesday night, said after the game when asked about Betances' injury. "We've been working together since spring training. He's been working hard to get back here. He was so happy in Toronto when he pitched that game. It's hard."

Betances returned to the Yankees this past weekend and made his season debut Sunday against the Blue Jays. He struck out both batters he faced, and, following the second strikeout, he hopped off the mound, which is something he's been doing pretty much his entire career. Manager Aaron Boone said the hop caused the injury.

"When he jumped on the mound the other day, I think he came down a little awkwardly," Boone said. "I don't think he thought anything of it. Didn't say anything at the time. When he came in today, he was sore. Going through some tests, he couldn't do some things like getting up in his tip-toes. ... Let's go get some imaging of this, and it revealed the partial tear."

Added Boone: "Obviously frustrating. About as freak as it can be. We'll deal with it. Obviously we've dealt with a lot of things this year and this is another one. We'll support Dellin as best we can through this. He's a big part of this still going forward."

The Yankees are planning to lean on their bullpen heavily in October, and Betances was expected to provide additional depth behind core relievers Zack Britton, Aroldis Chapman, Chad Green, Tommy Kahnle and Adam Ottavino. Instead, the team will rely on the same five core relievers in October, and Boone believes that will work just fine.

"We've been one of the best teams in the sport all season, and I would say our bullpen's been one of the overwhelming strengths of this club, and that doesn't change," Boone said. "There's no denying the impact that Dellin is. He's been one of the handful of the best relievers in the game for several years now. We know how great he is and what a difference-maker he is. But we certainly have the people there to continue to have our bullpen be a strength, and we'll just have to have Dellin's support from the side like he's been giving all year."

Betances, 31 and a free agent at year's end, had missed most of the year with a nagging shoulder issue. Prior to that, he had been one of the most durable relievers in the game, leading all full-time relief pitchers in innings (373 1/3), batters faced (1,505) and strikeouts (607) from 2014-18. Betances is a four-time All-Star with a career 2.36 ERA.

With a win on Tuesday, the Yankees improved their record to 99-53. The Yankees are likely to clinch the American League East within the week, and could well earn home-field advantage throughout the playoffs.