Boston Red Sox player Brock Holt steps up to the plate at Hadlock Field as the Sea Dogs’ designated hitter during Thursday night’s game against the New Hampshire Fisher Cats.

PORTLAND — Many of the 4,875 in attendance for Thursday night’s Portland Sea Dogs game left after the seventh inning, when Brock Holt struck out in his fourth plate appearance of the night.

Jeremy Barfield and the Sea Dogs rewarded the faithful who stuck it out to the end with a walk-off grand slam and a comeback 8-7 win over the New Hampshire Fisher Cats.

Barfield ripped an 0-2 slider from Justin Shafer over the Maine Monster in left as Portland salvaged the third game of the three-game series after being shut out in the first two.

“That’s what I saw (the first two pitches) — slider, slider, and then he hung another slider,” Barfield said. “I knew in that situation he was coming with it. He left it up and gave me a chance to do something with it. I don’t really trust that wall too much, but I knew when I got it that that thing was out.”

The grand slam capped a big night for Barfield, who is the son of former Toronto Blue Jays and New York Yankees outfielder Jesse Barfield. He went 4-for-5 with three runs scored.

Holt, who returned to action last weekend in Pawtucket after being shut down by the Boston Red Sox on May 21, did not have a night to remember in the second start of his three-game rehab stint with the Sea Dogs. He went 0-for-4 with a strikeout.

“All he needs is some at bats and to get his timing back,” Portland manager Carlos Febles said. “This is a guy who has been out for more than a month, I’m not sure how long. The more at bats he gets, the more comfortable he will be.”

Holt, a 2015 American League All-Star, is on his third rehab stint this season since being diagnosed with vertigo after playing six games in April for the Red Sox. He is scheduled to play again Friday when Portland opens a four-game set against Reading with a doubleheader at Hadlock Field. The first game is scheduled for 5 p.m.

Holt, who went 1-for-3 with a single in Wednesday’s 2-0 loss, started as the DH and hit second in Portland’s order Thursday. He lined out to short in his first at-bat, then grounded out to second in the third inning.

Danny Mars’ leadoff single in the fifth gave Holt a chance to do some situational hitting in his third at-bat. Mars broke for second on Fisher Cats starter Conner Greene’s 1-1 pitch to Holt, who pulled it for a line drive to right field. Harold Ramirez barely had to move for the catch and tossed to first to double-up Mars.

Portland rallied from a 2-0 early deficit to take a 3-2 lead in the fourth when left fielder Jake Thomas misplayed a Cole Sturgeon fly ball. Barfield and Chad De La Guerra scored on what was scored a triple. Jordan Procyshen singled to score Sturgeon.

“You could see (Greene’s fastball) pretty well,” Barfield said. “Velocity isn’t really everything in the game. That’s why we were able to get a lot of hits (nine) off of him.”

Portland starter Teddy Stankiewicz, who allowed 12 hits and two walks in 5 2/3 innings, couldn’t hold the lead in the sixth. Mars tried to bail him out with a diving attempt on Richard Urena’s bloop to left but came up short and allowed New Hampshire to score two runs. Lopes made it 6-3 with an RBI single.

Holt had a chance to tie it when he stepped in for his fourth plate appearance in the seventh with two on and two out. After battling back from down 1-2 in the count, he looked at a 3-2 pitch from Greene over the outside corner for strike three.

After the Fisher Cats made it 7-3 in the top of the eighth, the Sea Dogs finally started on the comeback trail in the bottom of the frame with three consecutive singles off reliever Daniel Young and a ground out by De La Guerra that cut the margin to 7-4.

Portland loaded the bases with one out in the ninth after singles by Deiner Lopez and Mike Olt (who was pinch-hitting for Holt) and a walk by Rafael Devers (0-for-4).

Both teams finished with 15 hits on the night, with Sturgeon, De La Guerra and Henry Urrutia collecting two apiece for Portland. Tim Lopes went 4-for-5 with an RBI for New Hampshire.

Brock Holt, center, jokes around with Sea Dogs’ players and coaches in the dugout during Thursday night’s game against the New Hampshire Fisher Cats.

New Hampshire Fisher Cats third baseman Tim Lopes knocks down a hard line drive during Thursday’s game agasint the Sea Dogs in Portland. Although the batter was safe, Lopes kept the ball in the infield and prevented extra bases on the play.

New Hampshire Fiser Cats’ Richard Urena safely dives back to first before Sea Dogs’ first baseman Henry Urrutia can put the tag on him during Thursday night’s game in Portland.

New Hampshire Fisher Cats’ Tim Lopes slides into second with a double before Sea Dogs shortstop Chad De La Guerra can make a play on the throw from the outfield.

Portland Sea Dogs pitcher Teddy Stankiewicz delivers a pitch during Thursday night’s baseball game agasint the New Hampshire Fisher Cats at Hadlock Field in Portland.