Michael Morse has been recalled from his rehab assignment in Tacoma and will join the Mariners in Boston on Tuesday for their upcoming road trip, which also includes a series in Baltimore.
Morse has been on the disabled list with a quad injury since June 22, though he was injured on May 28 and played sparingly before landing on the DL.
To make room on the roster, outfielder Jason Bay has been designated for assignment. Bay, 34, was hitting .204 with 11 home runs and 20 RBI this season.
Seattle now has 10 days to trade, release or outright the contract of Bay to the minors.