Jason Bay launched a go-ahead solo home run in the bottom of the eighth inning, paving the way for a 6-3 Boston victory at Fenway Park that seemed in doubt just one half-inning earlier.
A throwing miscue by catcher Victor Martinez, coupled with a single from Paul Konerko, put runners on the corners with no outs in the top of the eighth, but Hideki Okajima and Manny Delcarmen rebounded by combining to retire the side in order and end the threat.
Missed opportunities have become an unpleasant theme for Chicago (63-63), which fell back to .500 for the first time since July 29 and is now tied with the Twins for second place, 4 1/2 games back of Detroit. The White Sox are hitting .224 (44-for-196) with runners in scoring position over their past 21 games.
"That's been our problem all year long," said manager Ozzie Guillen, whose team dropped its 31st game of the season after holding a lead. "If you watch this ballclub closely, you'll see we're really bad with men on third base and less than two out -- maybe the worst team in baseball right now.
"Every time we got a man on third base, we didn't do the job, and that continued to bite us. Good teams do that. Good teams score the guy from third base and take advantage of that. We're not doing that right now. We're not doing that period -- all year long."
A first-inning RBI groundout from Dustin Pedroia was the difference through two innings, but the teams traded runs two frames later before starters Freddy Garcia and Jon Lester settled down in the middle innings.
Making just his second appearance of 2009, Garcia scattered five hits and fanned five over 6 1/3 innings of three-run ball for his first quality start since May 28, 2007.
"I was just trying to pitch my game," Garcia said. "I was making good pitches when I was behind the count. I like to pitch here [at Fenway]. It's a lot of fun."
"I had a great feeling about him coming into this game," Guillen said of Garcia. "He loves to pitch against good teams in big games. He did very well."
Jayson Nix knotted the score at 1 with one swing of the bat to lead off the third, drilling a 95-mph fastball from Lester over the Green Monster, but Kevin Youkilis singled home J.D. Drew in the bottom of the inning to put Boston (72-53) back on top, 2-1.
Scoring did not resume until the seventh, when the White Sox hung a two-spot to chase Lester.
With one out and runners on second and third, third-base coach Jeff Cox elected not to send Konerko home on a fly ball to right by Alex Rios, which drew a poor throw from Drew. The decision proved inconsequential, as Konerko scored one batter later on a Lester wild pitch that was also a swinging third strike on Alexei Ramirez.
Nix followed with a line drive to third base that glanced off the glove of Mike Lowell for an RBI single.
The Red Sox answered in the home half of the frame, as Martinez greeted Matt Thornton by lofting an RBI single to left that plated pinch-runner Nick Green.
Boston breathed life back into Chicago one inning later, as Okajima misplayed a popup off the bat of leadoff batter Carlos Quentin for an infield single. Moments later, a normally routine throw from Martinez back to Okajima sailed into center field, moving Quentin into scoring position.
Konerko's single pushed Quentin to third, but Okajima sat down Jermaine Dye on a popup to shortstop and struck out A.J. Pierzynski before Delcarmen (5-2) got Rios on a popup to second to end the frame.
"It's tough in close ballgames like that when you're not getting those situations taken care of," Scott Podsednik said. "As a whole, you're just not going to win too many ballgames. We're not scoring many runs, so when you leave those guys on third with less than two outs, it's going to make it tough on our pitching staff."
Bay made it tough on Scott Linebrink one out into the eighth, tattooing an ill-located splitter well over the Monster.
"As long as he's there, I have to bring him out," Guillen said of Linebrink (3-6), who is sporting a 7.71 ERA in 11 2/3 innings since the All-Star break. "I called on him, and he got [beat]. No matter what I do, I call on the wrong guy. I guess it's my fault to call the wrong people every time we bring those guys in."
Martinez and Jacoby Ellsbury smacked RBI hits later in the inning to give the Red Sox a three-run cushion heading into the ninth, when Jonathan Papelbon nailed down his 30th save of the season.
Five contests into a span of 20 games in 20 days, the White Sox already stand at 1-4, not the best of starts for a team with playoff aspirations.
"Right now, this is a man's game," Guillen said. "I know what I've got. I'm still waiting for it to show up."
John Barone is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.