ST. PETERSBURG -- The right hamstring soreness that forced Bryan Woo to exit during the fourth inning of his start on Monday night against the Rays landed the Mariners' second-year righty on the 15-day injured list one day later, after an MRI revealed what Woo called a ¡°low-level" strain.

In a corresponding move, reliever Collin Snider was recalled from Triple-A Tacoma.

Sitting in the visiting dugout at Tropicana Field on Tuesday, a visibly distraught Woo was unsure of his timeline to recovery. He wouldn¡¯t be eligible to be activated until July 9, six days before the All-Star break.

¡°Just taking it day by day right now,¡± Woo said, later adding, ¡°It's the first time I've ever dealt with something like this. So I don't know much about it. I just know as a general sports knowledge that hamstrings can be kind of irritating and delicate sometimes. So, like I said, I'm just going to listen to the training staff and take it one day at a time.¡±

The Mariners aren¡¯t yet sure how they¡¯ll fill Woo¡¯s rotation spot, but they do have three off-days before he¡¯s eligible to return and in theory could skip his turn and still keep everyone on regular rest. The balance, though, is that they¡¯d like to use those days for extra rest among the others in the rotation.

¡°It's really important to give these guys the extra blow if you can,¡± Mariners manager Scott Servais said. ¡°But we've got two off-days there pretty close. So hopefully we can use that to our advantage.¡±

Woo said he didn¡¯t experience any pain in his leg until his 60th and final pitch of a 4-3 loss, after which he was seen grabbing the area and stretching it out. Upon conferring with Servais and head athletic trainer Kyle Torgerson, Woo unsuccessfully attempted a warmup pitch, unable to complete his delivery down the mound before releasing the ball to the plate.

¡°I didn't feel anything before,¡± Woo said. ¡°And then trying to throw a practice pitch or whatever it was, I just didn't feel like I could like push off the way I wanted to. ... I've never had any like lower-body stuff, hamstring stuff. So I kind of didn't really know what was going on. I just knew that I felt different. It didn't feel like anything I had felt before, so I just wanted to be extra cautious about it.¡±

To that point, Woo had pitched as well as he had all season on Monday, averaging a 2.3 mph uptick on the velocity of both his fastballs, which were consistently topping 97 mph. He gave up five hits with zero walks and three strikeouts while surrendering just one run, which scored after he departed and Tayler Saucedo entered.

¡°It was probably the best I've felt all season,¡± Woo said.

Woo wasn¡¯t sure how active he¡¯ll be able to keep his arm while sidelined, but he¡¯s hopeful that he¡¯ll at least be able to continue to throw.

¡°That's the key,¡± Servais said. ¡°You don't want to shut down your throwing. Again, he won't be coming down the slope any time soon, but you've got to keep throwing.¡±

The hamstring issue is the latest blow during a frustrating year in which Woo has been electric but struggled to stay healthy.

Woo missed the first six weeks of the schedule due to right medial elbow inflammation, exited early in his 2024 debut after it tightened up on him, skipped a June 11 start due to the issue, underwent an MRI for it -- which came back clean -- then was admittedly rusty in his first start back last Wednesday in Cleveland.

When on the mound, he¡¯s been among the Mariners¡¯ best players, with a 1.77 ERA, 213 ERA+ (league average is 100), a 0.69 WHIP, with 28 strikeouts, three walks and a .428 OPS against. He¡¯s already been worth more wins above replacement in just eight starts in 2024 (1.1) than in 18 during an impressive rookie season (1.0), per FanGraphs.

¡°It's obviously been a tough season, I guess, so far, just dealing with injuries,¡± Woo said. ¡°I finally feel like I've got a night where I'm feeling good, the ball is coming out well, the stuff feels like it's getting back to where I feel like it could be and then, yeah.¡±

Snider was recalled to give the Mariners a fresh bullpen arm after they turned to six relievers on Monday and four on Sunday, when Bryce Miller was relieved after four innings after surrendering six runs in Miami.