KANSAS CITY -- Needing to beef up their bullpen after a one-inning start by Felix Hernandez in Monday’s 13-5 win over the Royals, the Mariners called up rookie right-hander Erik Swanson from Triple-A Tacoma prior to Tuesday’s game at Kauffman Stadium.

Right-handed reliever Chasen Bradford was placed on the 10-day injury list with inflammation in his right shoulder to open a spot for Swanson, the Mariners’ No. 9-ranked prospect, per MLB Pipeline.

Swanson, 25, threw five scoreless innings while allowing six hits with no walks and eight strikeouts as Tacoma’s Opening Day starter last Thursday, and he'd been scheduled to start again Tuesday before getting word Monday night that he needed to head to Kansas City.

Swanson was acquired along with No. 1 prospect Justus Sheffield and outfielder Dom Thompson-Williams from the Yankees last winter for standout lefty James Paxton. Swanson eventually figures to be targeted for a rotation role.

“This is Swannie’s first taste of the big leagues, but he knows who he is,” Mariners manager Scott Servais said. “Even though he doesn’t have any experience at this level, he’s probably one of the more mature guys in understanding how he gets them out.

“We’ll use him out of the bullpen in more of an extended role. Not a matchup guy, but somebody who can come in and give you two, three, four innings. I’m a big fan of bringing guys up even if they’ve been starters in the Minor Leagues into this role in the bullpen. I do think it breaks them in and makes it a little easier for them.”

Swanson’s addition means that of the 25 players currently on the Mariners’ Major League roster, 15 are new to the organization this year. If Swanson appears in a game, he’ll be the fifth player to make his MLB debut this season with the club, joining outfielder Braden Bishop, starter Yusei Kikuchi, reliever Brandon Brennan and utility man Dylan Moore.

Swanson said he knew he’d be called up at some point this season, but was surprised the move came this soon. What went through his mind when he received word from Mariners farm director Andy McKay?

“A lot of stuff,” he said. “ I was pretty emotional. Very, very happy. It was kind of cool to be able to share it with some of my teammates that were there as well. Just pure excitement for the most part. Getting to make that phone call to my family and tell them was pretty awesome. My mom started crying. My wife started freaking out. It was a pretty special moment.”

Bradford has Minor League options, but will remain with the club for now while rehabbing his shoulder. He had pitched 6 1/3 innings over five appearances, allowing seven hits and three earned runs for a 4.26 ERA and one save. The 29-year-old threw two innings in Monday’s win, allowing five hits and two runs in a 30-pitch outing.

Bradford said his shoulder felt fine when he was throwing, but grew tight after the game when he had trouble lifting it. He’ll take a few days off and expects to be ready to return as soon as possible.

Worth noting

• Servais said Swanson is one of the candidates to pitch in relief of Kikuchi when the Japanese lefty is limited to one inning in one of his starts toward the end of April. The plan with Kikuchi is to give him a short start about once a month to limit his workload in his first season of transition from Japan, where pitchers typically start just one time a week.

“We’ll just have to wait and see how it falls, who is rested, who is available to eat up innings in that type of ballgame,” Servais said. “He’s certainly one of the guys whose name did come up when we talked about who could fill in in that role.”

Servais said Roenis Elias won’t be considered for that role as the club will go with one of its pitchers who has been stretched out to be a starter in Tacoma.

• Shortstop Tim Beckham was held out of the lineup for a second straight day to rest a tight right hamstring. Servais said Beckham could have started, but the decision was made to allow his leg one extra day of rest as a precaution against re-injury.

• Hernandez said he was feeling a little better on Tuesday after a bout of stomach flu knocked him out of Monday’s start after one inning. He remains on schedule to make his next start Saturday against the Astros at T-Mobile Park.

“He still doesn’t look great. I don’t think he’s eaten a whole lot in the last couple days,” Servais said. “Hopefully he can get his strength back. We certainly need him to take the ball when his turn comes around next time.”