Saltalamacchia came off the bench and turned on a 96-mph fastball, depositing it into the right-center-field stands for the first walk-off homer of his career.
"Last time I faced him, he pumped fastballs right by me, so I knew I had to be ready," Saltalamacchia said. "I was just looking for a fastball and was able to get a fastball over the middle of the plate and do something with it. To be able to pull that one out at the end against this team, it was a tough game all night. It felt good though."
"To square that pitch up right there is pretty impressive," said manager Joe Maddon.
The loss snapped the Rays' three-game winning streak and denied them a chance to move into a first-place tie with the Orioles in the American League East.
David Price went seven strong innings but took a no-decision. The left-hander exited after 115 pitches and went at least seven innings for the fifth straight start, tying the longest streak of his career. He allowed one run on eight hits and struck out five against three walks.
"It's a good lineup, we played them close and I'll put Rodney out there any time," Price said. "He's been phenomenal for us all year long and it just happens."
B.J. Upton kept the Rays in the game both with his bat and his arm.
The center fielder threw out Dustin Pedroia at home in the sixth inning on a single up the middle by Adrian Gonzalez. The throw beat Pedroia to the plate and he was tagged out while trying to jump over Jose Molina. It was Upton's fifth outfield assist this year.
"That was a great throw," Price said. "He threw it through the cutoff, a one-hopper right to Molina. That was the play of the game."
The Red Sox got on the board first with an RBI single three batters later, but Upton's outfield assist kept the game within reach.
Upton started the seventh inning with a single before advancing to third on a single by Matt Joyce. Ben Zobrist's sac fly scored Upton, and when left fielder Daniel Nava threw home, Joyce took advantage and reached second.
Luke Scott brought Joyce home with a single. He is 11-for-27 with eight RBIs against Beckett in his career. Scott, who was at the center of the benches-clearing scuffle on Friday night, was booed each time he stepped to the plate.
But in a close game, there was no retaliation from the Rays for Red Sox reliever Franklin Morales plunking Scott the night before.
"I was pleased with both teams, I thought we were great, I thought they played well, too," Maddon said. "Both teams played a well-played baseball game and [Boston] happened to win."
Tampa Bay didn't get a hit off Beckett until Molina singled in the third. The Rays did not have another baserunner, though, until the two-run seventh.
Beckett allowed two runs on four hits in seven innings. He walked none and struck out five on 91 pitches.
Beckett has not lost to the Rays at Fenway Park since Sept. 27, 2006, and overall since April 30, 2009. The right-hander is 4-0 with a 1.08 ERA and 37 strikeouts in his last seven starts against Tampa Bay dating back to Sept. 12, 2009.
Price pitched himself out of trouble all night, allowing a baserunner in all but one inning. He quashed any hopes of a Red Sox rally in the seventh, getting David Ortiz to pop out with runners on the corners and two out.
"That was my biggest focal point tonight. We had some good defensive plays that were able to help me out and we held them tight," Price said of pitching with runners on base.
But Rodney couldn't tie the Rays' record for consecutive saves to begin a season, with 16. That record is still shared by Rafael Soriano (2010) and Al Reyes ('07).
"I'll be confident in him tomorrow if he's in there," Price said. "He's our guy. Saltalamacchia has been on the bench all game long. He hit a 96-mph fastball, [and] that's not very easy to do. Got to tip your cap to that guy and get one tomorrow."