MANCHESTER, N.H. — For the second straight night, the Portland Sea Dogs let a game against the New Hampshire Fisher Cats get away at Northeast Delta Dental Stadium.

Thursday night, a fielding error opened the door to three runs in the eighth inning and the Fisher Cats rallied for a 6-4 win.

On Wednesday, New Hampshire scored twice in the seventh to grab the lead in a 3-1 victory.

“We were in a really good position there to win a ballgame,” said Portland Manager Billy McMillon. “That ground ball there to lead off the eighth that kind of got the wheels going. It’s frustrating because the guys busted their hump the whole game … It’s just we failed there at the end and that’s kind of tough, like a punch to the gut, you know.”

The Sea Dogs, who won the opener of the series 7-2 on Tuesday night, fell to 27-46. New Hampshire improved to 33-38. The series concludes at 7:05 p.m. Friday.

The Sea Dogs squandered an effective outing by Luis Diaz, who was looking for his first win in almost a year, as well as nice Double-A debuts by left-handed reliever Williams Jerez and first baseman Sam Travis.

Diaz allowed seven hits and three runs, with three strikeouts and a walk over his five innings and was in line for the victory. His last win came July 5 at New Britain. He remained at 0-6 this season.

“There were some things in-game that he worked on: Locating off-speed pitches and stuff, and he got a little bit better at that today,” McMillon said. “From that regard there was some development on his part.”

Jerez, a converted outfielder called up Wednesday from High-A Salem, came on for Diaz and allowed one single over two innings.

“He looked good,” McMillon said. “A lot of poise. Threw strikes. A lot of confidence out there. I look forward to seeing him pitch some more.”

Travis and Manuel Margot, in his fourth Double-A game, sparked a three-run fourth that gave Portland a 4-3 lead.

Travis, who flied out to center field in his first Portland at-bat in the second inning, hit a first-pitch double to left to open the fourth. Margot followed with another first-pitch double to score him. Keury De La Cruz followed with a walk and Marco Hernandez knocked in two more runs with a single.

Travis was 1 for 4 for the night.

“He’s going to give us some professional at-bats,” McMillon said. “He looked like he belonged. He didn’t look overwhelmed, overmatched. It’s going to be exciting with him, Margot, Jake Romanski, seeing what those guys can bring to the ballclub. They had really good at-bats and got us going, and that’s good. Some guys can get nervous when they get to another level, but those guys were right in the middle of it and they looked the part.”

Margot had two of Portland’s 10 hits.

But in the end, second baseman Carlos Asujae couldn’t handle a Shane Optiz grounder in the eighth and the Fisher Cats rallied off reliever Madison Younginer.

NOTES: David Chester, who played first base Tuesday night for the Sea Dogs and was the designated hitter Wednesday, was placed on the disabled list Thursday. … Marco Hernandez and Cole Sturgeon joined Margot with two hits for Portland.