Pierzynski's well-placed drive into the gap in right-center -- in which right fielder Wil Myers and center fielder Desmond Jennings literally ran into each other -- completed a 3-2, 10-inning win for the suddenly rolling Red Sox.
"Good placement," said Pierzynski. "I hit the ball really well. They were playing me so deep. They were playing no doubles and I hit it right between them and they kind of ran into each other. It was nice to score the winning run. A lot of emotion in that game, a lot from both sides, it was just a big win."
That's five wins in a row for the Red Sox, coming directly after a 10-game losing streak.
This one had all kinds of drama, which started when Rays ace David Price drilled Red Sox slugger David Ortiz in the back on a first-pitch fastball in the bottom of the first.
Last year, in Game 2 of the Division Series, Price served up two homers to Ortiz and expressed frustration after the game that the slugger took so long to round the bases.
Ortiz thought the incident was over when Price apologized to him the next day. That's why Ortiz was so upset when he was plunked Friday by the first pitch Price threw to him since last October's meeting.
"I had a lot of respect of the guy, man, but it's over," said Ortiz. "I have no more respect for him. Last year we kick his [butt] in the playoffs, he went off, talking [trash] about everybody. We kind of got to talk on the phone. We kind of straightened things out. He was kind of upset. Me as a veteran I kind of let him know how things go in this game.
"Later on he called me and apologized because he knows he was wrong. He apologized in public. He apologized to myself. Everything was cool. So first at-bat of the season against him he threw at me. I mean, it's a war. It's on. Next time he hits me he better bring the gloves. I have no respect for him no more."
A warning was immediately issued by home-plate umpire Dan Bellino, and Red Sox manager John Farrell was ejected. Farrell was furious that Price didn't get ejected.
"You know, David's a heck of a pitcher," said Farrell. "He comes in with two hit batters and eight walks on the year. He comes in with the lowest walk rate in the American League. When he throws a ball and hits David Ortiz in the back, there's intent to that. They can dispute that all they want. There's intent to that pitch.
"As emphatic as Dan Bellino's warning was, it sure seemed like Dan Bellino felt like there was intent as well. I disagreed with it. He took the ball out of our hand."
Price denied intent.
"I've got to establish my fastball in," said Price. "I've got six lefties in that lineup. It's my favorite side of the plate to go to. I've got to establish it in."
The walk-off win was the second in as many nights for the Sox. Jonny Gomes started the winning rally when he was hit by a pitch from Juan Carlos Oviedo with one out.
Pierzynski stepped up next and did the rest.
"I think given the last four days, we've been able to carry over with some momentum, with some late energy to push across a tying run and then A.J. with the big one-out [triple] there to drive in Jonny," said Farrell.
This win was particularly sweet for the Red Sox in that they came back from an early 2-0 deficit against Price, with whom they weren't happy.
Price hit Mike Carp with a high pitch in the right forearm in the fourth and the Red Sox were incredulous again that he wasn't ejected.
Torey Lovullo, Boston's first of three acting managers on the night, was so upset that he got ejected.
"Again, if we felt there was intent to hit the batter, he would have been ejected," said crew chief Jeff Kellogg. "We felt the pitch was certainly inside, but not intentional, so that's why he stayed in the game."
Though they were filled with emotion, the Red Sox stayed on task. Needing a big hit, the red-hot Xander Bogaerts delivered a towering RBI double off the Green Monster against Price to tie the game in the bottom of the seventh.
Bogaerts pumped his fist when he got to second.
"With all our coaches getting thrown out, the one thing we all stayed focused on was trying to win the game," said Bogaerts.
Brandon Workman gave the Red Sox 5 1/3 solid innings, giving up four hits and two runs. He walked three and struck out four.
"Brandon, in a young stage of his career, brings a certain level of dependability and us knowing what he's going to give us," Farrell said.
Workman's night ended when he threw a pitch behind Evan Longoria in the top of the sixth. Both sides had been issued warnings after the Ortiz plunking in the first. At that point, third-base coach Brian Butterfield, next up as acting manager, was automatically ejected.
"The ball was slick and it slipped out of my hand," said Workman.
Perhaps there was still lingering bad blood between the clubs after the events of Sunday, when the two teams got into a scuffle after Yunel Escobar took third on defensive indifference in the seventh inning when the Rays had an 8-3 lead.
The Rays extended their lead to 2-0 in the fifth on an RBI single by DeJesus against Workman.
Ortiz got at least a small measure of revenge against Price in the bottom of the fifth when he lined an RBI single to left. Bogaerts and Dustin Pedroia set the table with singles.
It wound up being Pierzynski who sent everybody home, as Myers, who had an infamous fielding gaffe in Game 1 of last year's Division Series, again came up on the wrong side of a play at Fenway.
"Just both of us trying to get to the ball," said Myers. "It was one of those balls where neither one of us knew who was going to make the play. Both of us just trying to get there and we got there at the same time."