ST. LOUIS -- The St. Louis Cardinals cleared pitcher Chris Carpenter to resume rehab from a lower back injury on Friday after the team received outside medical opinions about his comeback from nerve issues.

General manager John Mozeliak said the 38-year-old Carpenter played catch Friday and was scheduled for a light bullpen session Saturday. How the former NL Cy Young winner responds to that activity will determine a course of action.

Carpenter's back tightened after a bullpen session and weight work on Sunday.

"It looks like it's not going to be that big of a deal," Mozeliak said. "Obviously, this week's come and gone. Having said that, he can jump back on and start making progress."

Mozeliak said the back problem slowed Carpenter's rehab from an injury that caused numbness and tingling on the right side of his body. He didn't believe it was a major setback, although the team still is not counting on a contribution from Carpenter, and declined to provide a timetable.

"I just think that's a dangerous thing to answer," Mozeliak said. "The moment we start getting out in front of that, something may occur, so it's just better to sort of take this day by day."

Carpenter was a 21-game winner in his 2005 NL Cy Young season and was second after going 17-4 with a 2.24 ERA in 2009. In his career, he has missed most or all of five seasons due to shoulder, elbow and nerve injuries, and pitched sparingly last season after radical surgery to relieve nerve compression.