Haren's most recent loss came at the hands of the Mariners on Wednesday when he allowed two runs and five hits in 7 2/3 innings of a 2-1 loss. He struck out seven in the hard-luck decision, but fell to 13-8 on the year to go along with a 3.16 ERA.
"I go out there and do what I can. I haven't had the best of luck lately, but it was a tough loss for the team," Haren said after the game.
Haren has faced the Mariners 18 times and is 9-5 against them with a 2.51 ERA.
Joel Pineiro (6-6) earned his first win since July 9, going seven innings and allowing one run on five hits and a walk.
"It feels nice. I was able to keep the ball down and I mixed my pitches," Pineiro said.
Jordan Walden pitched a scoreless ninth to pick up his 28th save of the year.
The Angels still sit 3 1/2 games behind Texas for first place in the AL West.
Seattle, meanwhile, has been relegated to the role of spoiler and comes into tonight's opener having lost four in a row following an 8-5 setback to Oakland on Sunday. Dustin Ackley hit a two-run homer and Luis Rodriguez added two RBI for the Mariners, who have lost eight of 10 overall.
Blake Beavan (3-5) allowed four runs on seven hits over five innings to take the loss. The right-hander is 0-3 over his last five starts.
Hoping to turn things around tonight will be rookie Anthony Vazquez, who is 1-1 with a 11.57 ERA. After winning his big league debut, Vasquez was banged around by the Angels on Tuesday for eight runs (seven earned) and seven hits in just four innings.
"A little bit of it is nerves, but you can't make excuses," Vasquez said. "First time up here you're trying to get out of the gate the right way and it just hasn't happened."
The Angels have won 10 of their 16 matchups with the Mariners this season, including six of the seven meetings at the Big A.