Sean Rodriguez hit a two-run homer in the ninth inning off Boston closer Alfredo Aceves, and the Tampa Bay Rays rallied for a 4-3 victory over the Red Sox on Sunday afternoon, a day after losing in the final inning.
Will Rhymes went 3 for 3 with three singles and an RBI for the Rays, who lost Saturday night on a pinch-hit, two-run homer by Jarrod Saltalamacchia in the ninth off closer Fernando Rodney.
Clay Buchholz had his best start of the season and Adrian Gonzalez hit a three-run homer for Boston, which was about to move above .500 for the first time this season until Rodriguez hit a drive off Aceves (0-2) over the Green Monster with one out after Ben Zobrist walked.
Boston lost for just the fifth time in 16 games, but dropped two of three in the weekend series that was highlighted by a benches-clearing incident on Friday.
Jake McGee (2-1) retired Gonzalez, the only batter he faced, on a grounder to short to end the eighth with the bases loaded to earn the win.
Rodney pitched the ninth for his 16th save.
It's the latest the Red Sox (23-24) haven't been over .500 since late August of 1996.
Buchholz, who entered with a major league-high 7.84 ERA, scattered eight hits and allowed two runs over seven innings, walking one and striking out six in matching his season high with 111 pitches.
The Red Sox had given Buchholz a major league-best 8.76 runs in his starts, but they were unable to put together any sustained offense against Jeremy Hellickson until rallying in the seventh.
Trailing 2-0, David Ortiz drew a leadoff walk and Kevin Youkilis singled before Gonzalez lofted a fly ball down the left-field line that hooked into the first row of Green Monster seats just inside the pole.
Hellickson gave up three runs, seven hits, walked two and struck out three over 7 2-3 innings.
The Rays broke up a scoreless game with a run in the fourth. Matt Joyce had a one-out double and advanced on the play when right fielder Gonzalez's throw missed the cutoff, hitting off the top of Dustin Pedroia's lunging attempt in short right and rolling about 20 feet away. Zobrist then bounced to first, scoring Joyce.
Gonzalez played right for just the second time in Fenway Park due to a number of injuries to Boston's outfield.
The benches cleared Friday when Boston reliever Franklin Morales threw behind Luke Scott before hitting him in the right leg.
Rhymes' two-out RBI single made it 2-0 in the seventh after Rodriguez reached on a double, barely beating Pedroia's tag with a headfirst slide.
Hellickson, who had his worst start of the season against the Red Sox in Fenway on April 14, allowed just four singles in the first six innings and only one runner to second base. That came when Scott Podsednik reached with one out in the third and advanced on a ground out, but Pedroia ended the inning with a fly out.
Hellickson gave up five runs in five innings in Boston's second home game of the season in April.
B.J. Upton extended his hitting streak to 10 games with a single, matching his career best.
Buchholz had double plays turned behind him to end the fifth and sixth.
NOTES: Boston 3B Will Middlebrooks doesn't look like he's let his early success spoil his attitude. He was walking through the clubhouse before Sunday's game and Gonzalez yelled, "Franchise" but the rookie kept walking until Gonzalez yelled, "Will." It finally got his attention and he turned around. The rookie drove in nine runs in his first four games when he came up earlier this month, matching a major league record. ... The Rays had won the last 12 "walkoffs" they'd been involved in before Saturday night's 3-2 loss to the Red Sox. "It felt unusual," manager Joe Maddon said before the game. ... Boston entered the day with a major league-leading 181 extra-base hits. ... Rays 1B Carlos Pena hit leadoff for the fifth straight game.