He is now the ace of the Portland Sea Dogs’ staff.

And Brian Johnson certainly looks the part.

Johnson pitched a four-hitter over six innings Tuesday night.

But the Portland bullpen again failed as the Akron RubberDucks rallied for a 5-4 win over the Sea Dogs before 7,106 at Hadlock Field.

Akron scored two runs in the ninth on four hits off Sea Dogs closer Noe Ramirez (2-1).

Down 5-4, Portland loaded the bases in the bottom of the ninth with one out. But Ryan Dent lined out to the second baseman and Heiker Meneses grounded out.

Michael Almanzar paced Portland with a three-run homer in the third. Keury De La Cruz went 3 for 4 with a walk and an RBI double.

Johnson, 23, lowered his Eastern League-leading ERA to 1.87. He allowed one run and two walks, striking out five. In his 18 Double-A starts, Johnson has allowed more than two runs only twice.

In his six starts since a stinker on July 7 (seven runs), Johnson has allowed three runs (0.65 ERA).

With Henry Owens (and his 14 wins) moving onto Triple-A, Johnson becomes the leader of this staff as the Sea Dogs contend for their first playoff appearance since 2008.

In the fourth inning, after allowing a leadoff single, Johnson struck out the next three batters.

“He had a really good mix; really kept them off balance,” Portland catcher Carson Blair said. “He even had them looking off-speed and froze them with fastballs.”

With the loss, the Sea Dogs (75-48) saw their lead in the Eastern League East Division reduced to 1½ games over Binghamton, which was rained out Tuesday.

Almanzar’s fifth home run of the season gave Portland a 3-0 lead.

Johnson allowed his only run in the sixth on Anthony Gallas’ leadoff home run. Portland got it back on De La Cruz’s double for a 4-1 lead.

Reliever Roby Scott allowed two runs in the eighth, and then Ramirez gave up two.

In the past five games (four losses), the Sea Dogs’ bullpen has allowed 24 earned runs in 151/3 innings.

NOTES: Outfielder Kevin Heller, who arrived Tuesday, was in the original Portland lineup but was scratched before he showed up. Heller, 24, was a 40th-round draft pick from Amherst College in 2012. He was batting .253 for Class A Salem with a .374 on-base percentage … Portland replaced promoted catchers Blake Swihart and Matt Spring with Blair and Jayson Hernandez. Blair, 24, was hitting .262 in Salem. Hernandez, 25, who spent most of 2012 in Portland, often roves where needed. He began the year in Salem, and was recently with Triple-A Pawtucket. He currently is on the disabled list … Derrik Gibson’s move to Pawtucket appears permanent. His name tag has been removed from his locker, with his belongings boxed up … Outfielder Peter Hissey remains on the disabled list with concussion symptoms … Infielder Sean Coyle (sprained ankle) could return as early as Friday. … Adam Miller pitched one inning in relief for Akron. Once an Indians’ first-round prize prospect, Miller pitched for Akron in the first game of the 2006 Eastern League Championship Series against Portland. Miller was also scheduled to pitch the deciding Game 5, but the Indians held him out because Miller had exceeded the number of innings Cleveland wanted him to throw that year.

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