ST. LOUIS -- Right-hander Mike Mayers is unlikely to return to the Cardinals’ bullpen until after the All-Star break, manager Mike Shildt confirmed on Friday, after a second opinion of his shoulder injury confirmed that he’ll need “a couple months” of rest and rehab.

If there’s good news, it’s that Mayers will not need surgery to repair the right shoulder lat strain he was diagnosed with after exiting his appearance at Miller Park on Monday.

Mayers, who is out of Minor League options, broke camp with the Major League team and made eight appearances before exiting with discomfort around his shoulder. He held opponents to one run over his first 6 2/3 innings before being scored upon in both of his outings on the team’s last road trip.

New role for Reyes

While the objective is still to have right-hander Alex Reyes refine his command during his time with Triple-A Memphis, how the Cardinals will structure that work is changing.

Reyes is moving into the Memphis rotation and will make his first start of the season on Saturday. He’s expected to throw about 40-50 pitches in his first appearance, Shildt said, before building up that count as his arm strength increases.

The role change was initiated primarily for two reasons: It’s the role in which Reyes, a longtime top prospect, is most familiar, and it’s the best way to build in time for the 24-year-old to work on his pitches outside of game action. That’s because in between each start, Reyes will have a scheduled bullpen session to throw.

Prior to this shift, Reyes walked six and struck out four in three scoreless relief appearances.

“You think about a reliever’s role -- you get up, you get loose to get into a game and it’s not really an opportunity in a get-hot setting to work on your changeup or your breaking ball or your slider,” Shildt said. “So, [this is] creating more structure for Alex that he’s used to and getting him to work on his repertoire.”

The change of plans was not an indication that the Cardinals plan to bring Reyes back to St. Louis as a starter, Shildt said. It will, however, afford that option if it becomes more appealing.

“I think it speaks to a role that creates flexibility,” Shildt noted. “But that’s not the driving force of why he’s doing it.”

Rehab roundup

• Right-hander Luke Gregerson (right shoulder impingement) had his rehab assignment transferred to Memphis on Friday. Before the move, Gregerson made five consecutive appearances without allowing a hit while pitching for Class A Advanced Palm Beach and Double-A Springfield. Pitching on back-to-back days is one of the checkpoints the Cards still need to see Gregerson reach before considering him for the active roster.

• Right-hander Carlos Martinez (right shoulder cuff strain) threw about 30-40 pitches on flat ground from a distance of approximately 60 feet on Friday afternoon. He’s expected to throw a 30-pitch bullpen session on Saturday, after which he’ll be reevaluated. Martinez’s next step would then likely be a more aggressive side session or a return to Florida, where he could throw batting practice.

• Outfielders Harrison Bader (right hamstring strain) and Tyler O’Neill (right elbow ulnar nerve subluxation) continue to heal and are likely to be ready to come off the injured list next week. Bader is eligible to return on Wednesday, while O’Neill can come back two days after that. The Cardinals are considering sending O’Neill on a quick Minor League rehab assignment to get some at-bats before he’s activated.