TRENTON, N.J. — Left-hander Brian Johnson delivered another solid performance Friday night, helping the Portland Sea Dogs to a 4-3 victory against the Trenton Thunder.

The victory for Portland came in the opener of a four-game series over three days.

It also improved the Sea Dogs’ record to 21-10 this month – the best May in franchise history – guaranteeing they will finish with a better percentage in May than the 1995 club (18-11, .621).

“Everybody’s been contributing,” said Manager Billy McMillon, who was a member of the ’95 team. “It’s just not one guy carrying this team and that’s a credit to how the guys are going about their work every day.”

Since reaching Double-A for the first time May 3, Johnson has been stellar. He allowed three runs Friday, two earned, on five hits with seven strikeouts and three walks in six innings.

“He was around the strike zone a lot,” McMillon said. “He mixed up his pitches well.”

Johnson has a 2.04 ERA in six starts with the Sea Dogs with 29 strikeouts and 11 walks.

“One thing I’ve learned coming through the minor leagues with the Red Sox is you have no secondary pitches, they’re all primary pitches,” Johnson said. “Have fun and have faith in your stuff that you work on so hard on the four days in between (starts).”

After allowing a run in the first, Johnson cruised through the second and third before Peter O’Brien launched a first-pitch fastball over the fence in left leading off the fourth. It was the first homer of the season surrendered by Johnson, who went 58 innings without giving up a long ball.

Johnson has allowed just five homers in 1512/3 professional innings.

O’Brien leads the minors with 20 homers between Class A Tampa and Trenton.

“I thought it was a decent pitch,” Johnson said.

Johnson used a fastball, curve, cutter and change-up that he’s not afraid to throw in any count. He threw four straight changeups to one batter Friday.

“I want (hitters) to respect every pitch I have,” he said.

Johnson left with the score 3-3, but Portland went ahead for good in the eighth inning when Bo Greenwell walked with the bases loaded off Tyler Webb (1-2).

Portland took a 3-1 lead in the fourth on Heiker Meneses’ RBI groundout an inning after RBI by Matt Spring and Stefan Welch made it 3-1.

O’Brien’s homer and Carmen Angelini’s sacrifice fly in the bottom of the fourth erased the two-run lead.

Michael Olmsted (2-0) didn’t allow a run for the 10th time in 13 outings, going two innings and giving up one hit to earn the victory.

Robby Scott pitched a scoreless ninth but had to escape trouble for his first save in his second opportunity.

After loading the bases with a pair of singles and a walk, Scott got Gary Sanchez to ground out to end the game.

Sean Coyle of the Sea Dogs doubled in the fourth to up his hitting streak to 11 games and finished 2 for 3.

Since returning from the disabled list May 23, Coyle is batting .464 (13 for 28) with a homer and six RBI.