Oceanside High’s great effort was on the cusp of coming up short. After leading since the opening minutes – by a big margin in the middle of the game and by eight with two minutes to play – the top-seeded Mariners were going to overtime in the Class B South boys’ basketball championship game.

Yarmouth’s great comeback was almost complete. The defending state champion dug out of a big hole and tied the game at 62-62 in large part because of senior Stevie Walsh and his 15 fourth-quarter points.

The momentum and the odds seemed to suddenly favor Yarmouth. Every player on the roster had a championship ring already, either in basketball, soccer or football. Several, like Walsh, who scored 32 points, had three rings from the 2021 and 2022 soccer teams and the 2022 basketball team.

But it was Oceanside that pushed through in overtime Friday, responding to one last Walsh 3-pointer with a tip-in by Alex Collins for a three-point play that helped close out a 71-67 win at the Portland Expo.

“We were leading by eight and we should have put it away there, but they got back into it and we just had to finish it,” said Cohen Galley, who finished with 18 points, including four in overtime.

Oceanside (20-1), the top seed, won its 15th straight game and will play Orono (17-3) or Ellsworth (20-0) in the state final at 3:45 p.m. next Saturday at Cross Insurance Arena. The school formed in 2011 by the merger of Rockland and Georges Valley had played in one previous regional final, losing to Falmouth in Class A in 2016.

Yarmouth, which beat Ellsworth in overtime in last year’s state final, finished 16-5.

Galley’s twin brother, Carter, made eight of his first nine shots, including five 3-pointers, on his way to 22 points by halftime and 31 for the game. The Mariners led 20-7 after one quarter, and their lead peaked at 24-7. It rested comfortably at 16 for much of the second quarter and was as big as 13 in the fourth quarter.

But with eight seconds left in regulation and with his team ahead by two, Carter Galley missed two free throws, then fouled Evan Hamm after Hamm had rebounded the second miss.

Hamm made both free throws to tie send the game to overtime. Then came a clock malfunction that caused a 3- to 4-minute delay.

“I was glad that we had that little extra break. … (Yarmouth was) on a momentum high right there,” said Oceanside Coach Larry Reed. “It just gave us a few extra seconds to get our thoughts back.”

After its red-hot start, Oceanside maintained a comfortable lead but could never quite shake the Clippers.

“We don’t believe in giving up,” said Ilunga Mutombo, Yarmouth’s first-year head coach.

Walsh and Hamm both heated up in the second quarter, combining for 13 points to cut the margin to a manageable 33-24 at halftime.

After three quarters, Oceanside was ahead 46-38. It was 54-41 after Zeb Foster (eight points) scooped in a runner with a bit over five minutes to play.

Enter Walsh.

A slender 6-foot-1 guard with a mop of auburn-tinted hair and an unimposing physique, Walsh has earned chants of “Stevie Wonder” from Yarmouth’s fan section with championship-winning soccer goals and basketball exploits. In quick succession, he hit a 3-pointer and then converted a three-point play when he shoveled in a shot from below his knees as he was fouled.

Oceanside’s offense, meanwhile, had stagnated but seemed to be generating enough points at the free-throw line to keep Yarmouth at bay. The Mariners led 62-57 with 26 seconds left.

Then Walsh dropped in a long 3-pointer to make it 62-60, and the Clippers soon tied the game.

“We had all the momentum going into OT and (Oceanside) flipped that fully, so props to them. They did a wonderful job,” Walsh said.