Anaheim right-hander Ramon Ortiz shut the Mariners (48-23) down through 7.2 innings to outduel Seattle's Jamie Moyer and lead the Angels to a 2-0 win.
The score was the opposite of a day before, when Freddy Garcia paced Seattle to a 2-0 win Wednesday.
Seattle's lead in the American League West dropped to 6.5 games, as Oakland's win over Texas coupled with the Mariners loss in the hands of the Angels. The Athletics have won six games ina row. Anaheim remains in the distance, some 12.5 games back.
But the story Thursday was Ortiz, and the Mariners' inablity to score during the few chances they had against the 30-year-old.
The Angels (35-35) moved in front in the third innings, when Eric Owens lifted a homer just beyond the outstreched arm of Randy Winn in left field. Before that hit, Moyer had retired the first eight Angels in order.
Looking to answer, the Mariners loaded the bases with nobody out in the fourth, still down just 1-0. With Bret Boone on third base, Edgar Martinez on second and John Olerud at first, Mike Cameron stepped to the plate and could only manage a weak grounder. Ortiz pounced on the ball and threw home for the force.
The next batter, Randy Winn, struck out on a ball thrown in the dirt.
Jeff Cirillo, not exactly the person the Mariners want at the plate in clutch situation, then lifted a lazy fly to left field to end the inning.
Ortiz escaped the threat, en route to one of his top two outings of the year. He allowed six hits, walked just one and struck out six before leaving the game.
On April 29, Ortiz (8-5) pitched the Angels to a complete-game victory, allowing just one run against Cleveland. He went 0-3 in May, but moved to 4-0 in June with the win.
Brendon Donnelly got the final out of the eighth inning, and Troy Percival came on the mow the Mariners down in the ninth for his 11th save in 2003.
Moyer (10-4) took the loss, his second in a row after winning seven straight. The soft-throwing lefty did manage to take the Mariners deep in the game, however, going eight innings and allowing just four hits and two runs.
The Angels scored their second run in the fifth inning when Shawn Wooten and Benji Molina hit back-to-back singles, and Benji Gil scored Wooten on a sacrifice fly to deep center field.
Mariners' No. 1 pitching prospect Rafael Soriano, who was called up earlier in the week, made his first appearance since being recalled in the ninth inning. Soriano struck out the side, blowing away the heart of the Angels' batting order by striking out Darin Erstad, Tim Salmon and Troy Glaus.
Boone and Martinez each had two hits to lead Seattle. Four Angels had one hit.