A.J. Pierzynski was designated for assignment by the Boston Red Sox, who have 10 days to trade, waive or release the 17-year veteran catcher.
Red Sox manager John Farrell confirmed the move to WEEI radio on Wednesday.
Prospect Christian Vasquez was promoted to take Pierzynski's place on the roster and was to make his major league debut against the Chicago White Sox on Wednesday night, batting ninth.
Pierzynski was acquired as an unrestricted free agent in the offseason, signing a one-year, $8.25 million contract.
A two-time All-Star, Pierzynski played for the San Francisco Giants, Minnesota Twins, Chicago White Sox and Texas Rangers.
He is batting .254 in 72 games this season with 15 extra-base hits and 31 RBIs. He is a .300 hitter in 30 career postseason games, and had three home runs and drove in nine runs in 2005 as a member of the World Series champion White Sox.
The Red Sox are reportedly shopping other veterans, including right-handed pitcher Jake Peavy, ahead of the July 31 non-waiver trade deadline.
The 23-year-old Vasquez was hitting .279 with three home runs and 20 RBIs in 66 games for Triple-A Pawtucket.