The Orioles selected the contract of outfielder Heston Kjerstad, their No. 1 draft pick in 2020, on Thursday before starting a pivotal four-game series against the Tampa Bay Rays. The Rays trail the Orioles by two games for first place in the American League East.

Kjerstad was added after first baseman Ryan Mountcastle injured his left shoulder in Wednesday night’s game against the St. Louis Cardinals. However, Mountcastle was not placed on the 10-day injured list, and, according to manager Brandon Hyde, he’s day-to-day with left shoulder soreness.

“We got great news,” Hyde said. “He’s feeling a lot better … He’s not an IL candidate.”

Mountcastle, who missed time because of vertigo, hit .360 with five home runs and 19 RBIs with a .984 OPS last month.

“He’s a huge part of our offense, especially in August,” Hyde said. “I love the way he’s swinging the bat. He’s had a couple of rough games as of late. Such a threat at the plate,  a guy who can go deep anytime and take good at-bats. I’d love to see him back in there. Hopefully, he’s back soon.”

In 122 games with Norfolk and Double-A Bowie,  Kjerstad batted .303 with 21 home runs and 55 RBIs and a .904 OPS. He was pulled from Wednesday night’s game for a pinch-hitter. After the game, Norfolk manager Buck Britton told him he was going to the Orioles.

“This is something I’ve worked for my whole life, something I’ve thought about,” Kjerstad said. “To finally be here and be in the moment is awesome so far.”

Kjerstad was the second overall pick in 2020 and because of myocarditis, an inflammation of the heart muscle, didn’t play in 2021. His professional debut was delayed until June 2022 because of a hamstring injury in spring training.

Though he’s not in the starting lineup for Thursday night’s game, Kjerstad is excited to be part of a crucial series.

“Two great teams going at it,” Kjerstad said. “To be able to be part of the O’s, and hopefully contribute to them winning more games, chasing the pennant, definitely an honor to be part of this stacked lineup and wanting to contribute any way I can.”

During spring training, Kjerstad said he thought it would be possible for him to play with the Orioles this season.

“I wasn’t trying to focus on it. I was trying to show up and become a better player every day,” Kjerstad said. “Now that we’re here, I’m excited that it’s part of my journey this year and excited to see what comes.”

Kjerstad played 38 games at first base this year and said he’s ready to play there in the major leagues, but Hyde says he views him as a corner outfielder and designated hitter. He said he’d play him at first base only in an emergency.

“I’ve been working there every day, playing two games a week. It’s been good so far,” Kjerstad said. “Definitely had a lot to work between the beginning of the week and now. I feel comfortable over there. I came a long way this season. I still have some things to work on, some things to iron out over there.”

Left-handed reliever DL Hall, who played with Kjerstad, is excited about his promotion.

“A big bat. I think it’s huge for us to get another bat here that is obviously incredible,” Hall said. “It’s fun to watch him take batting practice. The ball just comes off his bat a little bit different than other guys.”

Hall, Gunnar Henderson, Grayson Rodriguez, Adley Rutschman and Jordan Westburg, all high draft picks, have been added since May 2022. Kjerstad is the latest addition.

“It’s what happens with good teams with good farm systems,” Hyde said. “They’re bringing up talented players, and Heston’s had a nice year in Triple-A. It’s been fun to watch him from afar. What he did in spring training, I was so impressed with. It’s nice to have him as an option right now to either pinch-hit off the bench or maybe get a start.”

Outfielder Ryan McKenna and left-hander Nick Vespi were optioned to Triple-A Norfolk. Right-hander Bryan Baker was recalled from Norfolk.

McKenna was hitting .254 with two home runs and 18 RBIs in 86 games. Vespi was recalled before Wednesday night’s game and was optioned for the fifth time. Baker was 4-3 with a 3.64 ERA in 45 games before he was optioned to Norfolk last month.

Infielder Terrin Vavra also was recalled from Norfolk and placed on the 60-day injured list because of a strained right shoulder. Vavra hit .245 with five RBIs in 26 games with the Orioles earlier this season.