Tampa Bay Rays right-hander Tyler Glasnow is expected to undergo Tommy John surgery next week, sources told ESPN, after attempts to rehabilitate a partially torn ulnar collateral ligament in his elbow left him still in pain.

While there remains a possibility that Dr. Keith Meister, who will examine Glasnow next week, will recommend against the procedure, the likelihood is that the ace of the Rays' pitching staff will miss the remainder of the 2021 season -- and perhaps all of 2022 as well.

When healthy, Glasnow, 27, has been a star for Tampa Bay. In 37 starts over the past three seasons, he is 16-4 with a 2.80 ERA and 290 strikeouts in 206 innings. Injuries have vexed him since 2019, however, and the hope is that the elbow procedure will allow him to reach his elite potential long term.

At 6-foot-8 and 225 pounds, Glasnow cuts an imposing figure on the mound -- and his raw stuff is even scarier. His four-seam fastball averaged 97 mph this season and regularly touches 100 mph, and he added a hard slider this season to complement a dastardly curveball that he used as his strikeout pitch.

The diagnosis of the partial tear in Glasnow's UCL came soon after Major League Baseball said it planned to enforce its foreign-substance rule. Glasnow was critical of the on-the-fly implementation of the rule, saying his inability to use a grip agent forced him to hold the baseball differently, leading, he believed, to the injury.

Though some pitchers have continued to play with partially torn UCLs, the majority wind up undergoing Tommy John surgery, a procedure in which a surgeon takes a tendon from inside the body or from a cadaver to hold the elbow together. Over the course of the rehabilitation process, the tendon morphs into a ligament and stabilizes the elbow, which bears the brunt of strain and stress during pitching.

Pitchers typically take a minimum of 12 months to return from Tommy John, and the timing of Glasnow's leaves open the possibility that he could return to the Rays for the pennant race next season. If he does choose to avoid surgery at this point, Glasnow could continue rehabbing for the next few months and reassess over the winter. Going into the 2023 season healthy, however, is an imperative for Glasnow and the Rays. It will be the last season before he hits free agency.