Boston's celebration of Jarrod Saltalamacchia's two-run homer with two outs in the ninth to tie Baltimore was delayed for a video review.
Red Sox fans did eventually get to celebrate, but the festivities were short-lived.
Ronny Paulino's single off closer Alfredo Aceves scored Mark Reynolds with the go-ahead run in the 10th inning and the Orioles remained perfect at Fenway Park this season with an 8-6 win over the Red Sox on Tuesday night.
Baltimore closer Jim Johnson had recorded 25 straight saves — including his first 17 this season — when David Ortiz singled with one out in the ninth. Johnson then got Kevin Youkilis to fly out before Saltalamacchia drove a 1-2 fastball the opposite way to left field.
Replays showed the ball barely cleared the home run line atop the Green Monster, and Saltalamacchia and Ortiz trotted home, setting off a wild celebration.
"I was just trying to put the ball in play and keep the inning going any way I can," said Saltalamacchia, who has homered in six of his last 14 games. "I knew I hit it good. I didn't think it was going to get out. I thought it was going to go off the wall and at least be a double."
Baltimore improved to 4-0 on the season in Boston.
Instead of getting his 18th save, Johnson (1-0) got his first win with a perfect 10th for Baltimore.
Alfredo Aceves (0-3) walked Mark Reynolds to lead off the 10th and he advanced to second on a bunt by Steve Pearce, who converted his second sacrifice of the game and put the go-ahead run in scoring position.
Paulino had been 0 for 4 before delivering a single to center to put the Orioles up 7-6. Pinch-hitter Ryan Flaherty and Endy Chavez followed with back-to-back singles to right, the second scoring Paulino and giving Baltimore an 8-6 lead entering the bottom of the 10th.
The Red Sox couldn't strike twice against Johnson, who had converted 25 straight save opportunities dating to last season.
The Orioles got five hits in the seventh — all singles — and scored three to go up 6-4.
Boston starter Jon Lester was pulled for Scott Atchison after Chavez led off the seventh with a single to left. Robert Andino singled right away off Atchison and J.J. Hardy followed with a single that scored Chavez and tied the game at 4-all. The Orioles still had runners at first and second with nobody out when Adam Jones grounded hard right to Atchison for a potential double play, but Jones was able to outrun the throw.
Boston intentionally walked Matt Wieters to load the bases with one out, then Reynolds blooped a single to right to score Andino and reload the bases for Pearce, who drove his second run with a single to right to make it 6-4. Matt Albers got out of the jam with no further damage when Paulino grounded into a double play.
Two of Baltimore's three runs were charged to Atchison, who had not allowed a run in a career-high 19 2-3 innings.
"We all threw well. It just wasn't our night from that end of it," Atchison said. "It seemed like when a runner got in scoring position, they found a hole. They hit a ball in the right spot. Those things are going to happen."
Baltimore starter Jason Hammel was pulled after throwing 106 pitches in five innings. He threw 31 in the fifth alone as Boston took advantage of an error and scored twice to tie the game at 2-2.
Mark Reynolds couldn't field Daniel Nava's grounder when it took a tough hop and was called for an error, which was overturned later in the game. Mike Aviles followed with a single, then Scott Podsednik laid down a sacrifice bunt down the first-base line. Reynolds was charging and fielded it quickly, but his throw to try to get Nava at third got past Steve Tolleson and the ball rolled into the photographers' area out of play.
Aviles scored on Dustin Pedroia's shallow fly to center to tie it at 2-all.
Notes: Pedroia returned after missing six games with a thumb injury ... The Orioles swept the Red Sox 3-0 last month in a series at Boston. ... There was a moment of silence before the game in honor of Springfield Police Officer Kevin Ambrose, who was fatally shot Monday while responding to a domestic call for help. ... The Red Sox optioned RHP Daniel Bard (5-6) to Triple-A Pawtucket earlier Tuesday. Manager Bobby Valentine said that the club felt Bard needs to work on his mechanics back in the minors before he gets another shot at making the Red Sox rotation. ... Boston activated outfielder Darnell McDonald from the 15-day disabled list.