After sending four rookies and a 40-year-old to the mound, the Red Sox sent Julian Tavarez, 33, out for the 11th inning. He surrendered a double to Jason Kendall and RBI singles to Bobby Kielty and Frank Thomas with two outs to give the A's the lead, with Kirk Saarloos closing out the game in the bottom half of the inning.
Jason Varitek hit an RBI single with two outs in the 11th, but Mike Lowell grounded out to Saarloos to end the game and leave the tying run on base.
The Red Sox have played 30 innings in their last two games -- 19 against the White Sox on Sunday -- losing both contests and falling to 2-4 in extra-inning games this season.
"Any time you are in an extra-inning game, if you make a mistake you can lose, but when we are home, you certainly feel better about your chances," Red Sox manager Terry Francona said. "We couldn't push a run across, and then they did. And they added the insurance run which ended up being huge."
Red Sox starter Jon Lester received a no-decision but was in line for the win when he left the game. Lester had to grit out a five-inning performance that saw him throw 103 pitches, only 54 of them crossing the plate for strikes. An anomaly among rookie hurlers, Lester has not lost a game in his first six starts.
"He is a very young man. I think what he has done has been outstanding. He's learning on the run," Francona said. "As he gains command and matures, those five-inning outings will turn into seven-inning outings. We are asking a lot of him right now."
Lester allowed one run and five hits, but he also walked five batters. The lone run off him came on a Nick Swisher home run in the third inning that barely cleared the 37-foot wall in left field.
"There's times when I feel pretty good about where I'm going, and then there's nights like this where I'm going to take a step back," Lester said. "But like I said, [I] kept the team in the ballgame [and] only gave up one run, so that's the biggest thing there. Next step is getting to the sixth, seventh [and] eighth inning and give the bullpen a chance to rest a little bit."
Lester created several jams for himself but was able to escape each one without a scratch. The most troubling scenario came in the fourth inning. After a Mark Kotsay single and a Mark Ellis walk, Antonio Perez worked a 2-0 count. Lester fearlessly fired three straight strikes and then got Kendall to ground into an inning-ending double play.
"It's frustrating, but it's all me. It's nobody else, it's all on me. I get myself into jams, walk people, get behind in counts [and] don't get ahead. [I've] just got to keep working, continually get better as best I can," Lester said.
The Red Sox initially jumped out to a 1-0 lead after Lowell hit a home run in the second inning off Esteban Loaiza that rocketed over the Green Monster.
Breaking a 1-1 tie in the third inning, Trot Nixon hit a long single off of the Monster after David Ortiz led off the inning with a double. After a Jason Varitek single, Lowell brought home Nixon on a fielder's choice.
Fellow rookie Craig Hansen relieved Lester after the fifth inning and threw a 1-2-3 sixth. Coming out for the seventh, Hansen could not replicate the previous inning's magic, giving up two singles to lead off the inning before getting Swisher to ground into a fielder's choice.
It was time to change pitchers but not to change themes. Francona brought out another emerging arm in rookie right-hander Manny Delcarmen.
Then, in what seemed like subject matter for an episode of "The Twilight Zone," normally sure-handed Mark Loretta let a Kielty ground ball roll under his glove, allowing the A's to tie the game at 3. The score stayed that way until the 11th.
"He just didn't look it into his glove. [It] probably happens one out of every thousand," Francona said.
"I just flat out missed it. I took my eye off it a little bit just to see whether the runner had gotten a good jump. It was a little mental lapse," Loretta said. "We're not going to be perfect, but those are frustrating mistakes. That one in particular. Overall [the defense has] been pretty good ... you've just got to turn the page."
In the bottom of the ninth, Nixon led off with a walk and Willie Harris was sent in as a pinch-runner. However, it was only moments later that the promising inning turned sour. Oakland pitcher Kiko Calero threw over to first, catching Harris frozen off the bag and retiring the potential winning run for the Red Sox in a run down.
"You try to do something big and sometimes you go out and you try too hard," Harris said. "I thought he balked personally. ... Obviously the umpire didn't think he did, so the right person didn't think he balked, so it's a caught stealing. It's part of the game.
"That situation there was a hit-and-run play. I was just waiting for him to get home. He did some kind of freaky move, and I couldn't get back."
Oakland reliever Huston Street (3-3) tossed 1 2/3 perfect innings for the win.
Howard Kussoy is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.