Pineiro, who has been on the 15-day disabled list since May 21 with a strained right groin, will be activated later this week and start Thursday in place of the injured Adam Wainwright. Pineiro threw a bullpen session before Tuesday's game against the Reds, after which Cardinals manager Tony La Russa confirmed Pineiro was ready to return to the mound.
"Pineiro feels 100 percent," La Russa said. "He threw a bullpen this afternoon and threw the ball well. Right now, we have an opening Thursday, and he's penciled in to start there in the last game of the series. He'll just take Wainwright's spot.
"We've just got to watch [Pineiro]. He threw a very impressive bullpen. He's ready, and we need him. It's a good combination."
Pineiro has missed 17 games since going onto the DL. He is 2-3 through eight starts with a 4.50 ERA. He'll go up against the Reds' Bronson Arroyo in the series finale.
"I felt fine out there," Pineiro said. "It was coming out of my hand fine and everything."
Todd Wellemeyer will rejoin the rotation Saturday against the Phillies after experiencing right elbow inflammation after his Thursday start at Washington. Wellemeyer and Pineiro return a bit of structure to a rotation laden with question marks and plagued with injuries, the most recent one to Wainright.
Wainwright was sent to the 15-day DL Tuesday with a sprained right middle finger he sustained after pitching five-plus innings Saturday at Houston. His timetable is uncertain and his status will be re-evaluated this week, Cardinals general manager John Mozeliak said.
"I don't know [how long he's going to be out]," La Russa said. "It's on his pitching hand, so you've got to keep your fingers crossed more than anything. We've got to hope for the best and prepare for the worst."
Brandon Harris is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.