BOSTON -- The losses and the frustration had been piling up for the Red Sox of late, and those troubles threatened to mount again on Monday afternoon.

This time, a slumping team took action to reverse its fate.

Travis Shaw emphatically welcomed himself back to Boston and the Red Sox – his original franchise -- with a walk-off grand slam at Fenway Park to seal an 8-4 victory in 11 innings over the Rangers.

• Box score

But it became possible when Garrett Whitlock did a brilliant job in relief (2 2/3 innings, one hit, one unearned run, no walks, four strikeouts) after Matt Barnes suffered his sixth blown save of the season.

And it became even more possible -- perhaps even probable -- when Rafael Devers swatted a game-tying 414-foot double with the Red Sox one strike away from defeat in the bottom of the 10th.

“Yeah, that’s a big hit by Raffy,” said Shaw. “He falls behind in the count right there. The guy is on first, too, so you’ve got to drive it in the gap for him to score on one hit, and he was able to do that. I’m pretty sure that’s a homer in 28 or 29 other ballparks. The game could have ended there, but the uniqueness of Fenway, it’s a double, but big spot right there, down in the count, two outs, and we needed it.”

Perhaps the stage was set before the game when veterans Xander Bogaerts, J.D. Martinez and Chris Sale spoke during an impassioned team meeting.

“We’re going to keep that in-house for the most part, but the biggest thing to come from it was just that we want to play energized,” said Alex Verdugo, who provided early energy with a two-run homer. “That’s it. It doesn’t matter if something good is happening, bad is happening. It feels good to hear that.

“When you’re in the box and hear your guys cheering you on from the dugout, it makes a hitter lock in a little bit more. Some people think that’s what Little Leaguers do. Well, that’s what brings energy. That’s what gets you going.”

Verdugo made sure that Devers heard him just before the slugging third baseman -- who is having a tremendous season but a tough August -- unloaded for his equalizing knock to the triangle in right-center that got Fenway roaring as Bogaerts scored all the way from first.

“And then Devers going down 0-2, kind of just yelling from the dugout, yelling at him, ‘Win this pitch. Win this pitch. Whatever happened was in the past. Learn from it, flush it, go forward, and just win that next pitch.’ That’s exactly what he did,” said Verdugo. “He drove it [almost] 415 feet. It’s great to see.”

After a clean 11th by Whitlock, Christian Vázquez bunted automatic runner Hunter Renfroe to third, and the Rangers made an error on the play, allowing Vázquez to reach with nobody out.

Texas manager Chris Woodward then issued an intentional walk to Verdugo, putting the game in the hands of Shaw, who had gone 0-for-5 while being used sparingly in his first week back with the Red Sox.

With the count full, Shaw got a 97 mph sinker from Dennis Santana and destroyed it, sending it over the Boston bullpen and into the bleachers for a game-ending slam that traveled a projected 423 feet.

“Huge. Huge hit. He worked the count. He's a guy that we know he can put a good at-bat together,” said Red Sox manager Alex Cora. “Usually he doesn't expand, and that was a huge swing for us.”

For Shaw, it was one sweet trot around the bases for his first Fenway homer since July 24, 2016.

“Yeah, it’s special. Anytime you get DFA’d and a team claims you and gives you a second life, it means a lot to get claimed,” said Shaw. “It shows that there’s still a role for you, whatever role that is down the stretch. Just looking to kind of help out. Good start today. Good first hit back. Wouldn’t have it any other way.”

It didn’t seem like the Red Sox were going to need all those late-game heroics when Nathan Eovaldi departed after seven masterful innings (four hits, one unearned run, no walks, seven strikeouts) with a 3-1 lead.

However, Barnes (15.19 ERA in August) couldn’t hold that lead in the ninth.

The Red Sox got some measure of momentum back when Whitlock came into a mess -- runners on second and third and one out -- and kept the game tied.

The Rangers took their first lead in the 10th on Nathaniel Lowe’s single through the shortstop hole that scored the automatic runner from second. The Red Sox had a counterpunch from Devers and a knockout blow by Shaw.

Though the Red Sox, who are 8-15 since July 29, trail the first-place Rays by 6 1/2 games in the American League East, they are right there in the AL Wild Card hunt, in possession of the second spot by one game over Oakland after Monday's slate.

“Today just felt good,” said Verdugo. “Obviously it sucked to give up the lead, but to fight back, chip back, to have, when it felt like the guys’ demeanors, the attitude, the quality of at-bats, it felt like none of that deteriorated. None of that went downhill.”