ANAHEIM, Calif. (AP) -- Hisashi Iwakuma had never lost to the Los Angeles Angels, and he set their first eight batters down with perhaps the best stuff Seattle manager Lloyd McClendon had ever seen from him.
And then Iwakuma walked Efren Navarro on four pitches. The Japanese right-hander and the Mariners never recovered in a loss that knocked them further back in the AL wild-card race.
The Angels became the first team in the majors to clinch a postseason berth on Monday night, with Matt Shoemaker pitching five-hit ball into the eighth inning of an 8-1 victory over Seattle.
Seattle trailed 8-0 before Humberto Quintero drove in the only run for the Mariners (80-69), who dropped two games behind Kansas City for the second wild card spot with their fifth loss in six games.
"We've played them extremely well, and truthfully, up until the time we took Kuma out of the game, they didn't really hit the ball that good," Seattle manager Lloyd McClendon said. "But they're the best team in baseball, so I don't take anything away from them."
Although the Mariners' offense was pathetic again, their problems rested on Iwakuma (14-8), who yielded six hits and a career-worst seven runs.
Iwakuma's career-long dominance of the Angels (5-0, 1.64 ERA) abruptly ended with two outs in the third. Although he had walked just 16 batters in his first 176 innings this season, Navarro and Mike Trout drew walks before Albert Pujols cleared the bases with a shot down the left-field line.
"I thought Kuma was dominating ... (and) he made it look pretty easy," McClendon said. "But a two-out walk on four pitches (to Navarro), and then the wheels just came off and he couldn't get it back together."
David Freese and Brennan Boesch homered for the big league-leading Angels (94-56), who reduced their magic number to three in the AL West race with their 11th victory in 12 games. Los Angeles is assured of at least a wild-card berth, but is four games ahead of Baltimore in the quest for home-field advantage throughout the playoffs.
Pujols left the game in the third inning with a left hamstring cramp after hitting a three-run double, while Shoemaker felt discomfort in his left side after his final pitch.
Pujols wrote off the cramp to dehydration on another hot day in Orange County, and he expects to play Tuesday. Shoemaker will have an MRI on Tuesday, but the pain had already disappeared after the game.
Shoemaker (16-4), who turns 28 next weekend, improved his own franchise record for rookie victories with his ninth win in 11 appearances since July 26. He pitched seven shutout innings and didn't allow a runner to reach third base before Logan Morrison doubled and scored on two groundouts in the eighth.
Tony Campana had a two-run single and Howie Kendrick had an RBI double in the Angels' 17th win in 20 games.
GAME OF FIRSTS
The Angels have the majors' highest-scoring offense largely because they get help from everybody with a bat. They loaded the bases in the fourth for Campana, who delivered his first RBIs for his new team. Boesch then hit his first homer for the Angels in the fifth, putting them up 8-0.
Mariners: Dustin Ackley returned to left field after missing six of the last seven games with a left ankle injury. He left in the sixth inning.
Angels: Josh Hamilton's injured right shoulder felt strong after three rounds of batting practice. The cleanup hitter might return as soon as Wednesday.
After three consecutive wins with their bullpen filling injured Garrett Richards' rotation spot, the Angels will try it again, starting with reliever Cory Rasmus (3-1, 2.80). Roenis Elias (10-12, 3.81) pitches for Seattle.