JUPITER, Fla. -- Chris Carpenter has nerve irritation that has caused weakness in his pitching shoulder and the St. Louis Cardinals' ace will be sidelined indefinitely.

The Cardinals made the announcement Friday, after Carpenter was evaluated in St. Louis this week. The team says there is no new nerve injury and the cervical disc injury that occurred earlier in spring training is a "non-issue."

The 2005 NL Cy Young Award winner is expected back in camp by Monday, but there is no timetable for his return to the mound.

Carpenter, who turns 37 next month, helped pitch the Cardinals to World Series championships in 2006 and 2011. The right-hander was 11-9 with a 3.45 ERA last year, leading the NL in innings (237 1/3) and starts (34). He threw 36 more innings in the postseason, going 4-0 with a 3.25 ERA in six starts.

Carpenter previously had nerve issues in the shoulder in 2004 when he missed the postseason, and in 2008.

He had been scheduled to pitch on opening day, a spot that will be taken by Kyle Lohse.