ANAHEIM, Calif. -- The Los Angeles Angels placed promising rookie catcher Logan O'Hoppe on the 10-day injured list Friday due to a problem with his left shoulder.

O'Hoppe is still undergoing tests before the Angels determine the severity of his injury, manager Phil Nevin said.

O'Hoppe first injured his shoulder on a swing Monday in Boston. He injured it again while hitting a single Thursday in the ninth inning of the Angels' road loss to the Yankees.

The Angels have been vague on the nature of the injury, but O'Hoppe said Thursday that it was "the same thing" that happened in Boston: "I felt a pop come out the back."

The 23-year-old prospect seized the Angels' starting job behind the plate out of spring training while Max Stassi is away from the team with a hip injury and a family emergency. O'Hoppe is batting .283 with four homers and 13 RBI in 16 games.

The Angels acquired O'Hoppe from Philadelphia near the trade deadline last season for outfielder Brandon Marsh.

Veteran Chad Wallach started at catcher Friday night when the Angels opened a seven-game homestand against Kansas City. Los Angeles also optioned reliever Jimmy Herget to Triple-A Salt Lake and recalled right-hander Austin Warren, while right-hander Justin Garza was designated for assignment.