Hisashi Iwakuma will make his first major-league start Monday against the Baltimore Orioles at Safeco Field, Mariners manager Eric Wedge announced before Friday's game.
Iwakuma will replace Kevin Millwood in the rotation. Millwood left Wednesday's game against the Oakland Athletics after 2-2/3 innings with a groin injury. Wedge said the Mariners will likely push Millwood's next start back until next weekend.
"I didn't want to put him on the DL because you just don't want him to go that long without pitching," Wedge said. "He's been throwing the ball pretty good, and I don't want him to go that long without pitching and lose that feel with the All-Star break coming too."
In 14 appearances, Iwakuma is 1-1 with a 4.75 earned-run average.
Iwakuma, 31, spent 11 seasons in the Japanese league before he signed a deal with the Mariners. The starter struggled in spring training with a 4.32 ERA in 8-1/3 innings and started the season out of the bullpen.
He wasn't available out of the bullpen Friday.