They recalled righty reliever Scott Atchison from Triple-A Pawtucket on Monday to fill his roster spot.
Lackey is 2-5 with an 8.01 ERA in his second season with Boston. He was scheduled to pitch Tuesday night against the Baltimore Orioles. The team has not said who will start in his place.
The Red Sox signed Lackey to a five-year contract before last season after eight years with the Los Angeles Angels. He went 14-11 with a 4.40 ERA in 33 starts.
Atchison pitched in one game for the Red Sox this season, allowing three earned runs in 3 2-3 innings. Last season, his first with Boston, he was 2-3 with a 4.50 ERA in 43 games.