The Portland Sea Dogs fought in a back-and-forth game to tie the New Britain Rock Cats 3-3 after seven innings Sunday afternoon.

But then one bad bounce had the Sea Dogs down again.

An error on a potential double-play ball led to four runs in the eighth inning and a 7-3 loss before 3,803 at Hadlock Field.

The Sea Dogs (11-19) made five errors in all as they dropped their fourth straight overall and seventh in a row at home.

New Britain leaves Portland after the series sweep with the Eastern League’s best record – 22-7.

“Five errors are uncharacteristic, and they led to three unearned runs,” Sea Dogs Manager Billy McMillon said. “With our margin, we can’t win much making five errors.”

Two of the errors came in the eighth, accounting for two of the four runs allowed by reliever Jonathan Aro (3-2) being unearned.

Aro began the eighth with a strikeout and then allowed a single and walk. Trevor Story hit a grounder to shortstop Mike Miller that looked to be a double play, but as Miller put his glove down the ball bounced up and off his leg, loading the bases.

“It didn’t even hit my glove,” said Miller, one of Portland’s more reliable infielders. “I didn’t see it (bounce) and it hit my leg. Aro did his job, got the ground ball, and I didn’t make the play.”

Tyler Massey followed with a tiebreaking two-run single and Tom Murphy singled home another run. One more run scored on second baseman Carlos Asuaje’s error.

“We’re in one of these ruts,” McMillon said. “If we continue to get good pitching and the bats come around more, we can win some games.”

Sea Dogs starter Mike McCarthy left after five innings with a 2-1 lead. He allowed five hits and one walk, striking out two.

Robbie Scott gave up a Will Swanner home run to lead off the sixth. New Britain then took the lead with an unearned run, set up by a throwing error.

Keury De La Cruz and Tim Roberson each had two hits for the Sea Dogs. Asuaje knocked in Roberson in the third. De La Cruz singled in the fourth and eventually scored on a double play.

Roberson singled home De La Cruz in the sixth to make it 3-3.

But the eighth doomed the Sea Dogs, who lost their fourth straight.

“Pitching is doing a good job,” Miller said. “Hitting – we’re getting on base but, situationally, not always getting the job done.

“It’s frustrating. Everyone wants to be doing better. The guys put in the work. We’re not seeing the results yet. I’m sure we will soon.”

NOTES: After the game, reliever Dayan Diaz packed up his gear between congratulations from teammates. He is headed to Triple-A Pawtucket. Diaz, 26, had a 1.15 ERA in nine games (152/3 innings), with 17 strikeouts and a 0.57 WHIP. … Portland plays host to the Trenton Thunder for its next series – Monday and Tuesday at 6 p.m. and Wednesday at 11 a.m. … Former Sea Dogs left-hander Henry Owens gave up no hits over four-plus innings for Pawtucket at Columbus but allowed three runs on six walks and a hit batter. Owens (2-2, 4.06 ERA) has struggled with his control since the start of the season, issuing 25 walks in 31 innings.