The first of several Orioles pitching prospects eyeing their 2021 debuts has arrived. The club on Sunday recalled left-hander Zac Lowther from their alternate site at Bowie, Md., designating veteran southpaw Wade LeBlanc for assignment in a corresponding move.

Lowther, the club’s No. 11 prospect, will work in the bullpen for the time being but is a candidate to start down the road, manager Brandon Hyde said. The O’s currently have a rotation spot open after No. 7 prospect Dean Kremer was optioned last weekend after pitching to a 6.75 ERA over his first three starts.

Lowther enjoyed a successful debut Sunday, pitching a scoreless ninth in the O’s 8-1 win over the A’s.  

“Very cool moment for him and a nice way to break him into the big leagues,” Hyde said. “I was pumped to watch him on the mound, and he didn’t disappoint -- threw strikes, showed multiple pitches, didn’t look nervous, though I’m sure he was.” 

LeBlanc had been serving as the long man in Baltimore’s bullpen; he surrendered four runs over 1 2/3 innings in Saturday’s 7-2 loss to the A’s, his lone spot start of the season.

The Orioles now have seven days to release LeBlanc or place him on outright waivers. He can remain in the organization if he clears waivers or he can elect free agency. LeBlanc has a career record of 46-47 with a 4.55 ERA over 245 big league games (120 starts) over parts of 13 big league seasons for eight teams.

“We really like Wade a lot,” Hyde said. “He’s a big-time pro. He was great in our clubhouse and one of the few veteran guys that we had. It’s not easy to have that conversation with somebody like that.”

Lowther received the big league call late Saturday night after his wife and young daughter, Isabel, had gone to sleep.

“The ringer was on loud, so I was scared of waking my daughter,” he said. “My wife rolled over and said: ‘What happened?’ I said, ‘I just got called up.’ She was like, ‘Is this a dream?’”

The O’s second round pick out of Xavier University in 2017, Lowther found success at every level on the strength of his pitch ability and ultra-high-spin fastball, which helped him lead the Eastern League in strikeouts and finish second in ERA in 2019. Lowther went 13-7 with a 2.55 ERA in 26 starts that summer at Double-A Bowie, where he anchored one of Minor League baseball’s best rotations alongside No. 8 prospect Mike Baumann, Kremer, No. 20 prospect Alexander Wells and Bruce Zimmermann.

He was slowed a bit by an oblique injury at the alternate site last summer, but he recovered enough to perform well in limited game action this spring, logging four scoreless innings in Grapefruit League play. Praising the work the Orioles development team did at the alternate site last summer, Lowther responded confidently to questions about his readiness on a Zoom call with reporters in March.

“I feel like I’m there,” Lowther said then. “The only thing stopping me right now is not being on the roster.”

“I feel like I’m ready,” Lowther reiterated Sunday morning. “When I got here today, it was like I belonged.”

The O’s couldn’t give Lowther much of a chance to make the club out of camp -- Zimmermann, Kremer and Jorge López earned their three open rotation spots over No. 10 prospect Keegan Akin, who opened the season in Bowie. Lowther then logged the O’s best alternate site start to date in their 10-3 win over the Nationals’ alt site team Tuesday, striking out five over four innings of one-run ball. He was promoted Sunday in part because Akin injured his left index finger with a kitchen knife recently, requiring stitches that will sideline him through at least the end of the month.

“You know injuries happen, and its part of baseball, so being able to have a goal in mind of how you want your season to go is something that goes into your work every day,” Lowther said. “My goal is to be here. The work was very intentional down there.”