BOSTON — Kevin Kiermaier felt he had something to prove to the Charlotte Stone Crabs, where he played in two games while working his way back from a left thumb sprain.

It took him all of one pitch.

“I’m sure they’re thinking, ‘Man, where was this a couple days ago?’” Kiermaier said, smiling, after homering on the first pitch he saw since returning to the majors and leading Tampa Bay to an 8-5 victory over the Boston Red Sox on Wednesday night.

“To be a fly on the wall in that room,” said Kiermaier, who went 1 for 8 with the Class A Florida State League team. “I know how baseball players are.”

Austin Meadows hit a three-run homer and Willy Adames also went deep for the Rays, who didn’t even need their trade deadline reinforcements to win for the fifth time in six games.

After closing three deals in the minutes before the 4 p.m. cutoff, the Rays jumped to a 5-0 lead against Boston starter Rick Porcello (9-8). The defending World Series champions made no moves, then went out and lost their third straight game at home.

“Your front office is trying to win, and that gives us a message: They’ve got our backs,” Kiermaier said. “It makes us all excited. It gives you that second wind you need in the dog days of summer.”

Ryan Yarbrough (10-3) came on for opener Andrew Kittredge in the third and went 4 1/3 innings for the win, allowing four runs and six hits with three strikeouts.

Kiermaier also tripled home a run and scored in the seventh, when the Rays made it 8-2.

Michael Chavis homered and Boston scored three in the bottom half before Colin Poche struck out Andrew Benintendi with runners on first and third to end the inning. Chaz Roe fanned Benintendi looking with two on to earn his first save.

Tampa Bay began the night a half-game behind Oakland in the AL wild-card race; the Athletics hosted Milwaukee later Wednesday night. The Rays remained 7 1/2 games behind the first-place Yankees in the AL East, with the Red Sox another 2 1/2 games further back.

“It’s August now. We know where we’re at — we’re in a big hole,” Boston manager Alex Cora said. “We have to play a lot better.”

J.D. Martinez had three hits, including his 23rd homer of the season, and Mookie Betts also had three hits. Boston has homered in 16 straight games at Fenway Park, the longest Red Sox streak since they did it in 17 in a row in 1969.

Porcello allowed six runs on nine hits and one walk, striking out seven in 5 2/3 innings before leaving with a 6-2 deficit and taking out two TV monitors in the dugout.

“I kind of wish I did that without cameras being on me,” he said. “I apologize to everyone that had to see that. It’s not a behavior that I feel like is representative to me and my personality. The frustration got the best of me.”

The 2016 AL Cy Young Award winner had been the beneficiary of the best run support in the majors over his last four starts, with the Red Sox scoring 49 runs while he was in the game. He was 4-0 in those starts despite allowing 19 runs in 22 2/3 innings.

TRADING TIME — The Rays acquired slugger Jesús Aguilar from Milwaukee and also picked up right-handers Trevor Richards and Nick Anderson from Miami. They sent right-hander Ryne Stanek and minor league outfielder Jesus Sanchez to the Marlins and also traded reliever Adam Kolarek to the Los Angeles Dodgers for Class A outfielder Niko Hulsizer.

NO BIG DEAL — The Red Sox made no trades at the deadline. President of baseball operations Dave Dombrowski said he didn’t want to give up too much for what was realistically only a chance at a one-game wild-card playoff that is essentially a coin flip.

“It’s easy to say to switch people (around),” he said. “Sometimes you need to fix the people you have.”

TRAINER’S ROOM — Rays: Placed INF Joey Wendle on the 10-day injured list with right wrist inflammation. Manager Kevin Cash said Wendle felt it on a swing in Toronto and waited a few days before telling the team. “He’s a pretty tough guy. For him to acknowledge that two or three days later, just know the way his mind works,” Cash said. “Hopefully this is close to a minimum stint. Four, five days of no swinging and get some treatment.” . Cash also said OF Tommy Pham hurt his hand on a slide recently and was available off the bench.

Red Sox: C Christian Vázquez took a wild pitch off his right knee in the seventh inning and seemed to be having trouble with it in the ninth. He fell to the dirt and needed to walk it off, then the training staff came out to check on him a few pitches later. He stayed in but limped back to the dugout after the inning.

UP NEXT — Rays: LHP Brendan McKay (1-1, 3.72 ERA) was recalled from Triple-A Durham before the game and is slated to start the series finale today.

Red Sox: RHP Andrew Cashner (10-5, 4.18) is set to make his fourth start for Boston since being acquired in a trade from Baltimore. He picked up his first win with the Red Sox last Friday against the Yankees.