With one out in the 10th, Jacoby Ellsbury singled off Brandon Gomes, stole second and took third when catcher Jose Lobaton's wild throw sailed into the outfield.
Manager Joe Maddon opted to play a five-man infield, moving Matt Joyce from left field to third base.
"We were just trying to set them up in the right place," Maddon said. "Matt was the only option. I just wanted him to stand on the bag to shorten the lead, which he did."
Upon moving to the hot corner, Joyce allowed that "it was a different view I haven't had in a while."
"The game's a lot closer, that's for sure," Joyce said.
Joyce's positioning did not factor into what happened next.
Shane Victorino threaded a ball between shortstop Yunel Escobar, who was shifted to the right side of the infield, and second baseman Ben Zobrist. Escobar dove to knock the ball down, but nothing could be done at that point. Ellsbury raced home to give the Red Sox the walk-off win.
"You bisect two guys on the same side of the infield, and then furthermore, the right speed," said Maddon about Victorino's hit. "It's just very unfortunate for us."
The loss moved Tampa Bay to 4-6 on the season and was particularly frustrating given the fact it had a runner in scoring position with no outs in the ninth and the 10th innings but failed to score. The Rays were 0-for-11 with runners in scoring position, and overall are hitless in their last 17 at-bats with runners in scoring position.
In the ninth, Joel Hanrahan walked Evan Longoria and Zobrist to start the inning. That earned the Red Sox closer a quick hook and a showering of boos by the Fenway faithful.
Koji Uehara took over to face pinch-hitter James Loney, who watched a called third strike for the first out. Escobar then popped out to shallow right field before Ryan Roberts popped out to second to end the threat.
"Loney was the best shot there," said Maddon when asked why he did not bunt Longoria over to third. "Loney has an ability to get a base hit and drive in the run. Again, the guys hitting [after Loney] are not really tearing the ball up right now. … If James had gotten a base hit, it was the right move."
Jose Molina led off the 10th with a hustling double to right off Junichi Tazawa that concluded with a barrel-roll slide into second. Kelly Johnson was brought in to pinch-run, but two outs later, Sam Fuld grounded out to first to end the threat.
"I had an opportunity earlier in the game to drive a run in," Longoria said. "Later in the game we had a couple of runners on second, nobody out that we didn't even give anybody else a chance to get a guy to third base with less than two outs. We didn't do a whole lot offensively today."
What happened late felt preordained given the way the game began. Desmond Jennings led off by hitting what appeared to be a single off Will Middlebrooks' glove at third, but instead of the ball continuing toward left field, it ricocheted in the air to shortstop Steve Drew for the first out of the game.
"I've never seen anything happen like that," Maddon said.
Jennings singled to lead off the third and scored from first when Sean Rodriguez doubled to left off Lester to give the Rays a 1-0 lead. David Ross answered for the Red Sox with a two-out homer in the fifth when he hit a 3-2 changeup from Price over the Green Monster to tie the score at 1.
"Watching a lot of video, he doesn't throw many changeups," Ross said. "He threw more today than most. I've only faced him one time before, but he usually throws a lot more cutter-fast, cutter-sinker. He was definitely throwing that changeup over.
"It was just one of those things I reacted to. I definitely wasn't sitting on changeup. I was sitting on fastball. A guy throwing that hard, it's hard to look anything other than fastball. … That changeup, it just was a four-seamer. I think he was trying to make a better pitch than he did."
Ross' homer was the fourth Price has surrendered in three starts this season. Nevertheless, the reigning American League Cy Young Award winner looked more like he did in 2012 on Saturday while holding the Red Sox to one run over six innings, striking out eight en route to a no-decision.
Lester matched Price's excellence by allowing one run in seven innings to also earn a no-decision.
Clearly, pitching is not the Rays' problem at this early juncture of the season.
"They have a good pitching staff," Longoria said of the Red Sox. "You have to give some credit to them, but if we're going to want to compete in this division, and this season in general, we're going to have to find a way to push across more than one run."