ST. LOUIS -- Prior to the I-70 Series opener against the Royals on Monday, Cardinals general manager Michael Girsch confirmed what was becoming apparent: prospect Alex Reyes' return from Tommy John surgery will come in the Major League rotation.
"We expect him to be in the rotation," Girsch said.
Reyes, ranked as the club's No. 1 prospect by MLB Pipeline, has started each of his three official rehab assignments, the fourth and final of which is scheduled for Thursday at Triple-A Memphis. The right-hander will prep as a starting pitcher in between at Busch Stadium.
Reyes is eligible to return from the disabled list on Monday, May 28, and he would be on turn to start the next day against the Brewers at Miller Park. He most recently struck out 12 over 7 2/3 innings in a dominant outing at Double-A Springfield.
Girsch said Reyes' return would likely precede the return of Carlos Martinez, meaning the Cardinals won't face a rotation logjam for at least a few weeks. But once Martinez returns, the club will face a difficult roster decision, with Reyes, Jack Flaherty and Luke Weaver in the mix for just two available spots.

Weaver rebounded from a tough four-start stretch to hold opponents to just one earned run over his past two outings. Flaherty had one of the best outings from a Cardinals starter this season against the Phillies on Sunday, striking out 13 over 7 2/3 innings. Not everyone can stay.
"Obviously, we have new information," Girsch said. "We adjust to what we have. Knock on wood, hopefully we get a bunch of guys healthy and start having more tough roster decisions like we had at the end of Spring Training."
Martinez begins program
Martinez began a throwing program on Monday, his first baseball activity since landing on the DL on May 9 with a lat strain. Girsch said it's possible Martinez will require a rehab start before returning to the rotation.

"He's starting the progression back after not throwing for about two weeks now," Girsch said. "So we will take it step by step and see how it goes."
More injury updates
• Girsch joked that he's fine with not making a roster move every day of the week, after the Cardinals have made one near-daily over the season's first 45 games. Girsch provided updates on an array of the club's 10 players currently on the disabled list.
• Adam Wainwright underwent a non-intrusive procedure on Monday where doctors inserted a microscopic camera into his elbow in search of the pain that's persisted there. It was the latest in a litany of tests the righty has undergone in recent weeks, which included an MRI and a bone exam. The results of the latest test were not immediately available.
• Basic hand therapy is the next step for shortstop Paul DeJong, who underwent a post-op consultation on Monday, Girsch said. The team specialist will give the Cardinals guidance on when DeJong can take the next step. DeJong broke the fifth metacarpal in his left hand when he was hit by a pitch on Thursday.
• Tyler Lyons is set to return from a sore back in the coming days. Lyons made a second -- and presumed final -- rehab appearance at Springfield on Monday.
• Luke Gregerson (shoulder and elbow soreness) still needs to see doctors before the Cardinals head to Pittsburgh later this week to find out when he can begin throwing.
• Girsch said catcher Carson Kelly (hamstring strain) could return when he's eligible on Saturday.
• Dominic Leone (nerve damage in right arm) remains out indefinitely.
• Yadier Molina still has a ways to go in his recovery from a traumatic hematoma sustained when he was hit by a foul ball earlier this month.
"He's seeing the doctor on Thursday," Girsch said of Molina. "That's how fast we will get some guidance on when he can start doing physical activity. He's been on significant rest so it's hard to project until he can start jogging and stuff like that."