"We wouldn't be in this situation without him," Seattle manager Don Wakamatsu said of his newfound closer. "But it's a credit to him. He's worked so hard. He started in spring training, bounced around from team to team a little bit and just came up on a mission this year. He's found a home here."
Aardsma's not one of the bigger-named closers in the AL, but he pitched a perfect ninth Sunday to improve to 17-for-18 in save situations.
"This year I've been throwing a lot of strikes," said Aardsma, who struggled with the Red Sox last season, going 4-2 with a 5.55 ERA before missing significant time with a strained groin. "Last year if I threw ball one it would have been like, 'Oh, here I go again.' This year it's not a big deal."
Just like their game-winning rally, the Mariners are quietly creeping up in the AL West.
The rally started when Takashi Saito (2-2) walked the bases full with one out.
Jason Varitek hit a two-run homer for Boston, which also lost Friday's series opener. The Red Sox had won their previous seven series overall. It was just their third series loss in their last 12 in Fenway Park.
Russell Branyan drove in the other two runs for the Mariners.
"It was a long inning for him," Boston manager Terry Francona said. "Because of lack of command you get in a situation where you have runners all over the bases and you have to play the infield somewhat in."
"I'm not usually the kind of pitcher to give up a lot of walks to begin with. I can't remember another incident like today," Saito said through a translator.
Roy Corcoran (2-0) worked 1 2/3 innings of hitless relief.
"We keep talking about guys stepping up," Wakamatsu said. "Corcoran was the story of the day. Here's a guy who hadn't pitched in seven days."
Varitek homered over the Green Monster after Rocco Baldelli walked to give Boston a 2-0 lead in the second.
Seattle scored runs in the third and fifth to tie it at 2.
Branyan doubled into the left-field corner to score Ichiro Suzuki, who singled leading off the third.
Woodward opened the fifth with a single, advanced to second on Ronny Cedeno's bunt single, moved up on Suzuki's line to right and scored on Branyan's sacrifice fly.
Jacoby Ellsbury stole his 35th base, becoming the first Red Sox player to reach that mark in consecutive years since Tris Speaker from 1912-14. He also became the first AL player to do it in consecutive years before the All-Star break since soon-to-be 2009 Hall of Fame inductee Rickey Henderson did it in 1988-90.
Boston starter Brad Penny gave up two runs, six hits, struck out six and walked one in six innings. He's winless in six of his last seven outings.
"You look at the last two games, the two guys pitched pretty well, sometimes you lose. It happens," Penny said.
Boston lost 7-6 in 11 innings on Friday night.
Seattle's Garrett Olson allowed two runs on fours hits, striking out five and walking four in 6 1/3 innings.
Olson escaped a first-and-third no out jam in the sixth when he caught off third Baldelli on Ellsbury's grounder back to the mound. Jeff Bailey then bounced into a double play.
- Francona rested DH David Ortiz and inserted Baldelli into his spot with the left-handed Olson starting. Ortiz pinch hit and lined out.
- LHP Erik Bedard, on the 15-day DL since June 8 with shoulder inflammation, is set to start Tuesday against Baltimore. Bedard threw 54 pitches in a simulated game Friday. "I just had a little thing in my back," Aardsma said afterward.
- Red Sox C Varitek wore a red-white-and-blue chest protector that he will auction for charity.