The Portland Sea Dogs’ grip on the Eastern League East Division lead had been slipping, as surging Binghamton has been making a run.

Portland put a stop to that, at least for a game, with a 6-4 victory Monday night before 6,162 at Hadlock Field.

The Sea Dogs (65-37) moved to 4½ games ahead of Binghamton (60-41).

Several contributed to the win, including an RBI from old friend Ryan Lavarnway. The former Sea Dogs catcher began a rehab stint with Portland on Monday.

Lavarnway, 26, is recovering from surgery on his left hand to remove a broken hamate bone. He played first base – making a diving catch on a hard grounder down the line – and went 0 for 4 with three groundouts (one for an RBI) and one strikeout.

“Still quite not up to snuff yet,” said Lavarnway.

Derrik Gibson continues to be the Brock Holt of Double-A – breaking out as a leadoff hitter while also moving to the outfield. Gibson went 4 for 5 to up his average to .328, now second-best in the Eastern League. Gibson also stole a base and scored two runs.

While individual numbers are impressive, Gibson was well aware of who his team was playing.

“It’s starting to get to the point in the season when you start to look at that stuff,” Gibson said. “But the game has not changed. You still try to play it like it’s April. That’s what we did tonight. Just stayed loose and played our game.”

Wilfredo Boscan did not get the win, but pitched well. Boscan made his third start for Portland and gave up one run on six hits over five innings.

“He looked really strong,” said Gibson, who had a good view from his spot in center field. “His two-seamer and breaking balls were working.”

Boscan, 24, is in his first year in the Red Sox organization, having pitched previously in the Rangers’ and Padres’ systems. Boscan and Mike McCarthy (9-4) have played the important long relief/spot starter roles for Portland.

McCarthy relieved Boscan and pitched a perfect sixth to preserve a 3-1 lead.

But Binghamton led off the seventh with a single and Brandon Nimmo’s two-run homer to tie it.

Gibson began the bottom of the seventh with a single. He stole second and reached third on a passed ball. Blake Swihart walked and stole second. Both runners held as Lavarnway grounded out.

Sean Coyle hit a high bouncer back to the pitcher and Gibson raced home. Swihart scored on a wild pitch to give Portland a 5-3 lead.

McCarthy gave up another home run (Brian Burgamy) in the eighth, but Stefan Welch answered with an RBI single, scoring Ryan Dent and Portland took a 6-4 lead.

Robby Scott pitched a scoreless ninth for his second save, lowering his ERA to 1.88.

NOTES: Coyle went 2 for 5 and is batting .326. His two RBI give him 49, second on the team to Swihart’s 53 … Third baseman Michael Almanzar sat out a second straight game after his left hand was hit by a pitch Saturday night. Almanzar said he expects to play Tuesday.