Angels All-Star right-hander Ervin Santana will open the season on the disabled list with an elbow injury.
An MRI scan traced discomfort in his pitching elbow to a sprained medial collateral ligament, the team said.
"We'll slow him down, let the stuff in his elbow calm down, and go from there," manager Mike Scioscia said.
"We don't anticipate that it's the sort of setback that will cost him an appreciable part of the season."
The 26-year-old Santana, a native of the Dominican Republic, was 16-7 with a 3.49 ERA in 2008 for the Angels, who won the American League West with a 100-62 record.
Santana, who signed a four-year, $30 million contract at the start of camp, struggled in his only start of the postseason, a Game 2 loss to the Boston Red Sox in the American League Division Series.