Wainwright, who will officially go on the DL on Tuesday, is suffering from a finger sprain. The Cardinals' de facto ace injured his right middle finger while pitching against the Houston Astros on Saturday.
Wainwright said he felt a little pain in his finger prior to the start. He had to be taken out in the sixth inning while pitching to Darin Erstad.
Wainwright is 6-3 on the year with a 3.14 ERA and 62 strikeouts in 13 starts.
But while the Cardinals got bad news from Wainwright, both Joel Pineiro and Todd Wellemeyer are cleared to rejoin the team after suffering from injuries. Brad Thompson also made his first rehab start at Triple-A Memphis.
Pineiro has been on the DL since May 21 with a right groin strain and likely will be activated this week. Wellemeyer experienced right elbow inflammation after his Thursday start at Washington and will rejoin the starting rotation immediately.
"All-in-all, the news is favorable on three of the four players," Cardinals general manager John Mozeliak said in a statement, "and in Adam's case we are hopeful that the prescribed rest will help him to avoid any long-term absence from the rotation."
Lee Hurwitz is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.