With right-handed reliever David Phelps arriving Friday, the Mariners cleared space on their 25-man roster by by optioning Max Povse, another right-handed reliever, back to Triple-A Tacoma just one day after being recalled.
The Mariners acquired Phelps on Thursday from Miami in a trade for four minor-league players: outfielder Brayan Hernandez and right-handed pitchers Pablo Lopez, Brandon Miller and Lukas Schiraldi.
Phelps, 25, served as a starter for much of his 10 professional seasons before shifting last season to the bullpen. He was 2-4 with a 3.45 ERA this season in 44 games for the Marlins with 51 strikeouts in 47 innings.