ST. LOUIS -- A day after Alex Reyes' long-awaited season debut was truncated after four innings, the Cardinals placed Reyes on the 10-day disabled list Thursday with what general manager Michael Girsch said was "a significant" right lat strain.
"It is not going to be a couple starts [that Reyes will miss], it is going to be more than a few starts," Girsch said. "We don't have all the information yet, so we don't know beyond that how long it's going to be, but it is not a minor injury and we're gathering more information."
The right-hander, who threw 73 pitches in the Cardinals' 3-2 loss to the Brewers on Wednesday, missed all of the 2017 season due to Tommy John surgery. Having another setback after a 22-month recovery was a tough pill to swallow for Reyes and the Cards.

"I don't know how to properly describe it," Cardinals manager Mike Matheny said. "You could see it in his eyes. He was beyond sad."

• Morning Lineup Podcast: Reyes back to DL
Reyes' velocity began to drop in the fourth inning against the Brewers, prompting the Cardinals staff to check on him. He was able to finish the inning with pitches back in the mid-to-upper 90's.
Reyes assured the staff he felt fine, but then realized something was wrong after the game.
"Postgame when the adrenaline went away, he was stiff and sore," Girsch said. "Stiff and sore enough that we knew we were going to DL him."
However, Reyes and the Cardinals were surprised at the extent of the injury after doctors checked him out Thursday morning. The club is in the process of setting an appointment for Reyes to see a specialist for a second opinion.
The Cardinals made a flurry of other moves Thursday, optioning outfielder Tyler O'Neill and right-hander John Gant to Triple-A Memphis and recalling first baseman Luke Voit, right-hander Mike Mayers and left-hander Austin Gomber in corresponding moves.
O'Neill, who hit home runs in three consecutive games from May 19-21, was hitless in his last 13 at-bats with 10 strikeouts during that span.
"Certainly after that hot start he was struggling, but also he just needs to play," Girsch said. "With how well Harrison [Bader] is playing as our fourth outfielder and getting some playing time as a starter, O'Neill is just not going to get a lot of playing time up here."
Gomber, who this past week was named as Pacific Coast League Pitcher of the Week, was recalled to the Majors last month but did not appear in a game for St. Louis. The rookie left-hander is 4-3 with a 3.60 ERA in nine starts for Memphis. He will be used as a reliever.
Mayers, who has appeared in 10 games (1-0, 2.63 ERA) for St. Louis this season, was optioned on Wednesday to make room for Reyes, but has immediately been returned to the roster as an injury replacement.
The right-handed-hitting Voit had a short stint on the Cardinals' roster in early May, but never saw any game action. He's batting .237 with one homer and 12 RBIs in 34 games for Memphis this season.
Injury updates
• RHP Carlos Martinez (right lat strain) will throw 60-70 pitches in a rehab start at Double-A Springfield on Thursday night. Girsch would not rule out starting Martinez in place of Reyes on Tuesday if all goes well.
• C Yadier Molina (pelvic injury with traumatic hematoma) resumed baseball activities and is scheduled to begin a rehab assignment Saturday at Springfield.
• RHP Matt Bowman (right finger blisters) threw a bullpen session. He will throw a couple more sessions before a decision is made as to when he will return.
• RHP Luke Gregerson (right shoulder impingement) began a throwing program.