SEATTLE -- Right-handed reliever Brandon Brennan, who has been sidelined since the opening week of the season with a strained left oblique, was reinstated from the 45-day injured list by the Mariners on Tuesday.

The move adds another fresh arm to Seattle’s bullpen, which absorbed 15 innings of work the previous two days due a short start by Justin Dunn on Sunday against the D-backs and a doubleheader on Monday vs. the A’s.

Jimmy Yacabonis, a right-hander who got the start in Monday’s second game, was designated for assignment to open a 40-man roster spot for Brennan’s return. Right-hander Seth Frankoff, who pitched in the second game as well, was optioned to the alternate training site to open a spot on the 28-man active roster for Brennan.

The club chose to keep utility man Tim Lopes on the 28-man roster after he was added as the 29th man for the doubleheader. That gives the Mariners an extra position player while shortstop J.P. Crawford remains on the bereavement list following a death in his family, with the bullpen now back to 10 relievers.

Brennan went on the injured list on July 27 after making one regular-season appearance, allowing one run on two hits and two walks in 1 1/3 innings in a 7-2 loss at Houston in the second game of the opening road trip. The 29-year-old posted a 4.56 ERA in 44 appearances last year as a Rule 5 rookie.

Frankoff reports now to the alternate training site after making two relief appearances for the Mariners, allowing five runs in 2 2/3 innings. The 32-year-old rookie spent the past two years pitching in Korea and signed with Seattle on a Minor League contract on Aug. 11.

Yacabonis is no longer on the 40-man roster and the club has seven days to trade, release or outright him to the Minors. The 28-year-old allowed one run on two hits and three walks and hit a batter in 1 1/3 innings in his spot start in Monday’s 9-0 loss and has a 3.86 ERA in 2 1/3 inning in two overall appearances with Seattle. He spent the last three years with the Orioles and now is 3-5 with a 5.71 ERA in 57 games (12 starts) in his MLB career.