Boston recalled right-handed reliever Brandon Brennan from Triple-A Worcester while optioning pitcher Phillips Valdez in a corresponding move.
The Red Sox needed help in the bullpen with Hirokazu Sawamura dealing with a hip injury and Valdez recently having seen extended work.
Brennan, 29, has 49 major league appearances under his belt, all with the Seattle Mariners. The California native is 3-6 with a 4.45 ERA in 54 2/3 big league innings. Brennan, claimed off waivers by Boston on May 3, has a 2.16 ERA in eight relief appearances this season for the WooSox.
Valdez on the year is 2-0 with a 4.24 ERA in 20 appearances out of the bullpen.