BOSTON -- The Rays have been here before: backs against the wall, their season on the line. They just didn’t expect to be back so soon.

After a 100-win season, the defending American League champions entered the playoffs set on winning the franchise’s first World Series title. That has been the goal since the moment they walked off the field after Game 6 of last year’s Fall Classic. But here the Rays are, one loss away from elimination, after dropping a 6-4 heartbreaker on Christian Vázquez’s 13th-inning walk-off homer in a wild Game 3 of the American League Division Series on Sunday night at Fenway Park.

Now, the Rays must win Monday night at Fenway Park to stay alive and send the series back to Tropicana Field for Game 5. If they don’t win the next two games, their dreams of returning to the World Series will be dashed without even getting out of the first round.

“We've got to win tomorrow. We don't really have many choices,” Rays manager Kevin Cash said. “Today was a really big win for them and a really tough loss for us.”

The Red Sox have the series advantage, two games to one. They have momentum on their side after cruising to a Game 2 win and celebrating at the end of Game 3. In postseason history, the Game 3 winner in any best-of-five series that was tied 1-1 has gone on to win the series 39 of 54 times (72%). And after using nine pitchers to get through 13 innings, the Rays will have to piece together Monday’s game without a set starter in front of what’s sure to be a lively crowd on the day of the Boston Marathon.

But the Rays hadn’t lost any faith as they left the ballpark Sunday night.

“I have the confidence, about 10,000 percent, that this team is going to come back and bounce back like we normally do,” infielder Yandy Díaz said through interpreter Manny Navarro.

Cash, his coaching staff and players like Díaz who’ve been around for three consecutive postseason appearances have plenty of experience in win-or-go-home situations. They won the 2019 AL Wild Card Game in Oakland, lost the decisive ALDS Game 5 in Houston the same year, then they emerged victorious in win-or-go-home contests in Game 5 of the 2020 ALDS against the Yankees and in Game 7 of the ALCS against the Astros.

And if the Rays don’t come back, they’ll have more than their fair share of “what ifs” coming out of this series, with a bunch of them stemming from the five-hour, 14-minute affair that unfolded on Sunday. None of those moments figure to be more frustrating than wondering what might have changed with a better bounce of the ball in the top of the 13th inning.

With two outs and Díaz at first base, Kevin Kiermaier ripped a line drive to right-center field. Díaz would have scored easily had the ball remained in play. Instead, it bounced off the 4-foot outfield wall, ricocheted off right fielder Hunter Renfroe’s hip and skipped -- “thankfully,” Renfroe said -- over the wall and into the Red Sox’s bullpen.

Kiermaier stood in shock, both hands on his batting helmet, near third base as umpires called it a ground-rule double and, per Rule 5.05(a)(8), placed Díaz at third base.

“The umpires explained it to me, so I can't go against that. The rules are what they are,” Kiermaier said. “But, man, that's a heartbreaker. I can't believe that happened or we don't get the chance to score right there. … Yandy would have scored standing up. It's a heartbreaker, plain and simple.”

• Ground-rule double in 13th causes confusion

Rather than having a one-run lead and another runner in scoring position, Mike Zunino came to the plate with runners on second and third and struck out swinging against Nick Pivetta. In the bottom of the 13th, Vázquez ripped a two-run, walk-off homer over the Green Monster off Luis Patiño to end a streak of seven straight scoreless innings by Tampa Bay’s bullpen.

“If we score that run, it puts pressure on them. It helps us relax a little bit,” Díaz said. “Obviously it changed a little bit once that play happened.”

But that call, memorable as it may have been, was not the only reason the Rays came up short. They once again surrendered an early lead, forfeiting the momentum created by Austin Meadows’ two-run homer off Nathan Eovaldi in the first inning, as starter Drew Rasmussen allowed three runs while recording only six outs.

The Rays rallied to tie the game in the eighth on Wander Franco’s first postseason home run and an RBI double by Randy Arozarena, who collided with first baseman Kyle Schwarber on his way to second base, though no obstruction was called. Manuel Margot was caught stealing to end the 10th after over-sliding at second -- a call, upheld after a replay review, Cash called “a little confusing.”

The Rays finished just 1-for-9 with runners in scoring position, stranding 10 runners overall. They struck out 20 times, tied for fourth most in a single postseason game, with eight in Eovaldi’s five innings and seven more in four innings against Pivetta.

“We had opportunities. We just didn't capitalize,” Cash said. “Their pitching was tough, but just a lot of swing-and-miss. When you're swinging and missing, there's not much you can do.”

Nor was there much the Rays could do but move on and hope that Monday won’t be the final day of a remarkable season.

“We've got to put our big-boy pants on and just come out and do everything in our power to try to win a ballgame,” Kiermaier said. “I told the guys after the game when we got back to the clubhouse: If there's any team who can do it, it's us. You have to believe that and come out ready to win a ballgame tomorrow and do whatever it takes.”