AUGUSTA — Maranacook was one of the few lower seeds no team wanted to see and the Black Bears showed why Monday night at the Augusta Civic Center.

Eighth-seeded Maranacook trailed for all but three minutes against top-ranked Boothbay Region but found itself in front when it mattered to pull off a 57-54 upset of the Seahawks in the Western Class C boys’ basketball quarterfinals.

Julian Aponte of Boothbay got a clean look on a step-back, game-tying 3-pointer from the top of the key at the buzzer, but it bounced off the front of the rim.

“He’s a good shooter and I thought he was going to nail that shot,” said Maranacook’s lone senior, Cam Brochu. “I guess it just didn’t happen and we got really lucky at the end there.

“It’s exciting. I knew we were going to come in not very highly seeded but we’re hard workers, and I knew we would end up with a win as soon as we got here.”

Brochu scored eight of his game-high 21 points in the fourth quarter, and Levi Emery had six points and 18 rebounds. Reserve Kyle Wilbur provided a spark with 14 points.

Maranacook (9-11) will play fourth-seeded Winthrop (16-3) in the semifinals at 8:30 p.m. Thursday.

“Cam is our emotional, physical and performance leader,” Maranacook Coach Rob Schmidt said. “He brings everything to this team that we want every player to be like. Without him we’re not here. He’s a tremendous leader and that’s what he does; he steps up when he needs to. It was a great effort.”

Boothbay (16-3) had two opportunities to put the Black Bears away, building a 10-point lead midway through the second quarter and 12-point advantage with less than three minutes remaining in the third.

Each time Maranacook had the answer. The Black Bears closed the third quarter on a 10-0 run, highlighted by six points from Wilbur, to cut the deficit to 45-43 heading to the fourth.

“Boothbay was really worried about him,” Schmidt said of Wilbur. “They saw him hit six 3s in the prelim game and knew where he was every time on the court. He stretched their defense out and hit huge shots.

“More importantly I think they were really focused on him and we were able to get some other guys involved at crucial times.”

Wilbur later tied the game with 3:44 to play by knocking down two foul shots, but over the next minute each team struggled.

Ultimately it was Brochu who stepped up, putting in a layup after a lengthy possession to put the Black Bears up 51-49 with 2:04 left. It was their first lead since midway in the first quarter.

“That was huge,” Brochu said. “As soon as we get ahead we like to push ahead and keep going.”