PHOENIX – The Twins have an opening in their starting rotation after they placed Chris Paddack on the 15-day injured list Tuesday because of right shoulder fatigue.

Paddack, whose IL stint was retroactive to Saturday, hopes to return for at least one start before the All-Star break. He agreed with head trainer Nick Paparesta and the coaching staff that he needed an IL stint after his average fastball velocity was down 2 mph when he pitched last Friday in Oakland.

"I want everybody to know that this ain't pain," Paddack said. "This isn't pain or discomfort. This is fatigue."

Paddack reported a "dead arm" after his last start, something he dealt with last month, too. In his past two starts, both against Oakland, he has yielded 10 hits and eight runs in seven innings with only three strikeouts. He owns a 5-3 record and a 5.29 ERA through 15 starts this season.

"I'm a guy that wants to take the ball," Paddack said. "I'm ready to take the ball every day. But I'm also a guy that's been through a couple of injuries, and I don't want to be a hero. And I think my body's been talking to me the past couple of starts."

Paddack, in his first full season back from Tommy John surgery, was prepared to have some of his starts skipped throughout the season. He wishes it came when he was pitching better, but he's confident this IL stint will help him pitch better later in the season.

"Yeah, it looks bad that I have a 5.29 ERA and didn't pitch well the past couple of outings," Paddack said. "Is that why? No. Just fatigue, and I want to give our team the best chance to win. If I'm throwing 90-91 [mph] out there and second-guessing my heaters or off-speed stuff, that's not putting us in the position that we need to be in."

Reliever Ronny Henriquez was promoted from Class AAA St. Paul for the Twins' series opener against the Arizona Diamondbacks. Paddack was scheduled to start Thursday, and the Twins are expected to call up a starter to fill his spot.

Louie Varland pitched Sunday, allowing 11 hits and 11 earned runs in 2⅓ innings, so he's not lined up to start Thursday on regular rest. That likely leaves 24-year-old pitching prospect David Festa and Caleb Boushley. Festa, who hasn't made his MLB debut, has posted a 3.77 ERA in 14 starts with 87 strikeouts and 24 walks in 59⅔ innings. Boushley has been used only as a reliever in the big leagues.

Paddack will be back in the rotation once he's healthy, Twins manager Rocco Baldelli confirmed.

Stewart making progress

Brock Stewart threw a bullpen session Sunday, and he's scheduled to throw again Wednesday and Saturday in Minnesota, Paparesta said.

The Twins will determine Stewart's next steps and potentially a path toward pitching in a simulated game when they return from their road trip next week.

"Brock is slowly and incrementally increasing his velocity," Paparesta said. "He goes full out and he's bouncing back well. I think those are good signs."

Stewart went on the injured list on May 3 because of right shoulder tendinitis. In the past two seasons, he's permitted three runs in 41 innings (0.66 ERA) with 56 strikeouts.

Etc.

* Twins reliever Justin Topa, sidelined because of a partial tear in his left patellar tendon, is scheduled to throw a bullpen session next week, his first since the beginning of May. His recovery timeline will keep him out through the All-Star break.

* Minor league pitcher Matt Canterino had a setback and was shut down from throwing because of shoulder pain. Canterino, 26, has pitched only 85 innings since he was taken in the second round of the 2019 amateur draft. He's scheduled to undergo a magnetic resonance imaging exam next week, which will be reviewed by Dr. Keith Meister, who performed his Aug. 2022 Tommy John surgery. "Matt ramped up for a little while into bullpens, then he had a little bit of a situation where we needed to pull back a little bit," Paparesta said.

* Brooks Lee homered for the fourth time in his last six games and the St. Paul Saints earned a 6-5 road win over the Iowa Cubs on Tuesday. Will Holland added a two-run homer.