SAN DIEGO -- The Mariners will open the season without one of their top young starters.

Right-hander Bryan Woo will open the season on the injured list with elbow inflammation, Mariners general manager Justin Hollander announced before Monday’s 4-1 exhibition win over the Padres. An MRI showed no structural damage to Woo’s elbow, but he will be shut down for seven days before beginning to throw again.

“He did not feel good going into his last bullpen, couldn't get loose,” Hollander said. “We cut it very short. Fortunately, [the] MRI, everything else came back very clean structurally. No damage to the UCL ... Just a little mild inflammation.”

Right-hander Emerson Hancock will take Woo’s place in the Opening Day rotation, and is scheduled to start April 1 against Cleveland. Casey Lawrence will start in Woo's place for the Mariners' second exhibition against the Padres on Tuesday.

Woo, 24, went 4-5 with a 4.21 ERA in 18 starts for the Mariners as a rookie last season and was set to open the year as their fifth starter. He has a history of injuries, however, and has never pitched a full season dating back to college.

Woo had Tommy John surgery his junior season at Cal Poly and was limited to just 57 innings in his first professional season in 2022. He broke into the Mariners' rotation midway through last season but spent two weeks on the injured list in August with forearm inflammation.

Woo’s workload as a rookie vastly exceeded his previous high innings total. He pitched 131 2/3 innings between the Majors and Minors last year, a jump of 74 2/3 innings from the year before.

“The thing to keep in mind about Bryan is [he] just hasn't pitched much,” Mariners manager Scott Servais said. “So there's certain things that he has to go through. Whether it's Spring Training, ‘Yeah, I can pitch with that. No, I can't pitch with that.’ You know, different things.

“And we want to be super cautious early in the year. We need this guy. We need all of our guys. So we're going to be careful with him.”

Woo had yet to pitch more than four innings in a start this spring, so Hollander and Servais cautioned that he will need time to build up once he begins throwing again. There is no set timeline for Woo to return to the Mariners' rotation, but the team is hopeful it won’t be long.

“His UCL graft looks great. There's nothing structurally going on,” Hollander said. “So once he's ready to go after this, hopefully after the seven days of shutdown, I don't anticipate it being a long build-up.”

Hollander also provided injury updates on a number of other Mariners players. Most notably, reliever Matt Brash will open the season on the injured list with elbow inflammation that has sidelined him since Feb. 21, but he is progressing in his return. Brash threw at 85% effort off the mound on Sunday and is scheduled to throw another bullpen session in the next three or four days.

“He's just going to continue to ramp up a little bit at a time on intensity,” Hollander said. “[We] sort of already tested it on volume and now we're just building intensity. I watched it … along with our medical staff and he felt good afterwards.”

Additionally, utility infielder Sam Haggerty will open the season on the injured list with a personal medical issue that Hollander said is “not a baseball-related issue.” Reliever Gregory Santos (lat strain) is scheduled to have an MRI on Thursday and will open the year on the IL. Eduard Bazardo (rotator cuff strain) will also start the season on the IL after missing all of Spring Training, but is slated to return by the end of April.