Millwood leaves game against A's with groin injury
After retiring Kurt Suzuki on a grounder to shortstop, Mariners manager Eric Wedge and trainer Rick Griffin visited Millwood on the mound and decided to remove him.
Hisashi Iwakuma came on in relief.
Millwood left Seattle's combined no-hitter June 8 with a strained groin after pitching six innings. Millwood was kept off the disabled list but didn't pitch again until June 16 against San Francisco.
The 37-year-old right-hander is fourth among active pitchers with 2,642 innings pitched during his 15 major league seasons.