The outcome eliminated the Angels from title contention in the American League West, handing the division crown to the Texas Rangers for the second straight year. Los Angeles still has hopes for a wild card berth, but the Angels fell 3 1/2 games behind Boston in that race.
It was a 1-1 contest heading into the eighth, but Kurt Suzuki led off the inning with a single, moved to second on a sacrifice by Scott Sizemore and took third when Jered Weaver (18-8) threw a wild pitch.
Jemile Weeks then hit a grounder to second baseman Maicer Izturis, who misplayed the ball for an error that allowed Suzuki to score the go-ahead run.
In the bottom half of the inning, Oakland starter Gio Gonzalez (15-12) walked two batters with one away and was relieved by Balfour.
Balfour retired Maicer Izturis on a groundout, moving the runners to second and third, and then walked Peter Bourjos to load the bases.
That brought up Howard Kendrick, who flew out to right to end the threat and all but end the Angels' season.