Josh Donaldson hit a game-tying two-run homer and then the game-winning RBI single in the bottom of the 11th inning, lifting Oakland to a 3-2 victory over Boston in the finale of a three-game set.
Matt Thornton (0-4) walked pinch-hitter Chris Young to start the frame, and Eric Sogard sacrificed him to second. Coco Crisp's grounder failed to move him, then Derek Norris drew a pinch-hit base on balls ahead of Donaldson's solid hit to center to end the contest.
"I really believe that the guys in this clubhouse really believe that we have one of the best teams in baseball," Donaldson said. "It's just one of those things, where when we get an opportunity to play a good team like the Red Sox or the Pirates or the Cardinals, we're out there sending a message that we are a good team, that we're for real."
Ryan Cook (2-2) turned in two scoreless relief innings to pick up the win for the Athletics, who hit the All-Star break having won seven of their last 10 and hold a two-game edge over Texas in the AL West.
In his 400th career appearance, Bartolo Colon allowed eight hits and two runs with four strikeouts over 6 1/3 innings.
Dustin Pedroia and Brock Holt knocked in a run apiece for the Red Sox, who dropped the final two games in the series but still hold a 2 1/2-game edge in the AL East over Tampa Bay.
Brandon Workman's first major-league start was nearly flawless over the first six frames.
"Obviously, I had a good outing," Workman said. "I was locating my pitches pretty well for the most part and had a lot of success with it, so it's something I think I can continue to do and build off of for the next time."
He yielded just one walk and no hits, but Crisp was a half-step ahead of Pedroia's throw on a grounder to second to start the home seventh. Two batters later, Donaldson drilled a pitch deep to left center to tie the game, 2-2, and signal the end of the young right-hander's outing.
Yoenis Cespedes began the bottom of the 10th with a single and took second when Sox shortstop Jose Iglesias' throw ended up in the stands. However, after Josh Reddick struck out, he was caught stealing third for the second out and Nate Freiman grounded out to end the threat.
The Sox left the bases loaded in the 11th when Holt was caught looking at a third strike.
Boston broke through in the sixth, as Jacoby Ellsbury, Daniel Nava and Pedroia combined on three straight singles to produce a run.
It was 2-0 in the seventh, as Mike Carp led off with a double and scored two batters later as Holt dumped a single to left.
The A's have won eight of their last nine home games with the Red Sox, dating back to last July, and 36 of 60 home tilts since the start of the 2000 season ... Oakland reliever Grant Balfour was a late addition to the American League All-Star squad ...Prior to the contest, the Red Sox recalled left-hander Drake Britton from Triple-A Pawtucket and optioned outfielder Jackie Bradley Jr. to the PawSox.