ATLANTA – The Twins will be without one of their top relievers until at least the All-Star break after Brock Stewart was placed on the 15-day injured list Tuesday with right elbow soreness.

Stewart has been a dominant setup man since he was called up at the end of April, allowing only two runs in 25 2/3 innings (0.70 ERA) while pitching primarily in the seventh and eighth innings. He's been almost equally as good against lefthanded hitters as righties, holding opponents to a .172 batting average.

He returned to Minneapolis on Tuesday for a medical resonance imaging exam, but the Twins are hopeful it won't be a long-term injury.

"It looks like Brock is dealing with some tendinitis," manager Rocco Baldelli said. "That's the initial read from the trainers and the doctors that have taken a look at him. I feel like there is a reasonable chance that we headed off this issue and hopefully he won't be down for too long, which is somewhat good news."

It will be a challenge for the Twins, who don't have a ton of experienced high-leverage arms in their bullpen. Oliver Ortega, a righty, was recalled from Class AAA St. Paul to replace Stewart's spot on the 26-man roster. They lost José De León to an elbow injury last Saturday that will require season-ending Tommy John surgery.

Stewart, who had been dealing with some soreness for about a week, won't be eligible to return from the IL until the first game after the All-Star break, July 14 in Oakland.

"His stuff looked normal for him, good stuff that he always has, so it's not like there was any red flag or any pitch that he threw where he felt anything noteworthy," Baldelli said. "He said a lot of what he was feeling is stuff he feels day to day. He said picking things up, opening doors, so it's kind of portraying itself and looking like some sort of tendinitis."

The Twins have Jhoan Duran and Griffin Jax cemented in the back of their bullpen. Baldelli expects lefthander Jovani Moran to face more lefties in high-leverage situations and Jordan Balazovic, who has made only three appearances, could see more opportunities in stretches where the opposing lineup is filled with righties.

"There is not going to be one person who fills into all of the innings Brock was throwing," Baldelli said. "That's not the way I see it playing out. I think we're going to end up matching up a good amount in those innings."

López throwing, return TBD

Twins reliever Jorge López has thrown bullpen sessions while on the IL because of mental health reasons, but there remains no timetable for his return.

López, who did not travel with the team on the road trip, said last week the time on the IL gave him a chance to reset mentally and he hoped to be back in the bullpen "as soon as I can." He is eligible to be activated from the IL on Friday.

"I will not be the person deciding that," Baldelli said. "This is going to be more the medical side of things, combination with the doctors and the trainers. We're going to have to get together and make a good collective decision for Jorge as far as when the best time is to bring him back and how that's going to look."

Before López went on the IL, he gave up 16 hits and 12 runs in his last 6 1/3 innings.

Etc.

• The Twins had four players named to MLB.com's updated top 100 prospect list: Class AA shortstop Brooks Lee (No. 21), third baseman Royce Lewis (No. 23), Class A-Advanced outfielder Emmanuel Rodriguez (No. 64) and second baseman Edouard Julien (No. 70).