DURHAM — Finishing the season unbeaten was one goal the Exeter High School boys’ basketball team set for itself this season. The number one goal, of course, was to win the Division I championship.

The Blue Hawks are one win away from reaching both.

Top-seeded Exeter raised its record to 20-0 and earned a spot in Saturday’s Division I final by beating fourth-seeded Londonderry 62-51 Wednesday night at the University of New Hampshire’s Lundholm Gym.

Exeter surrendered a 15-point lead in the third quarter, but led by three entering the fourth and outscored Londonderry 21-13 in the final eight minutes. The Blue Hawks finished the game on a 15-4 run.

“We’re happy to survive and advance,” Exeter coach Jeff Holmes said. “We hit some big shots. Made some big plays. Real happy for the guys. Real happy we went on that run.”

Sophomore Josh Morissette led all scorers with 25 points. He made a 3-pointer that gave Exeter a 52-49 lead with 4:02 to play, and the Blue Hawks pulled away after that.

“Right now it feels great to be able to say we’re going to championship Saturday,” Morissette said. “They went on a huge run and they hit shots, but we didn’t really panic. We were ready for the moment.”

Kevin Henry added 19 points for Exeter, which received a 10-point performance from Ryan Grijalva. Morissette, Henry and Grijalva each had a team-high six rebounds.

Exeter will face second-seeded Salem in Saturday’s Division I championship game, which is scheduled to start at 3 p.m.. Salem (19-2) knocked off sixth-seeded Portsmouth 40-26 in Wednesday’s first semifinal. The Blue Hawks beat the Blue Devils 43-33 in Exeter during the regular season. Exeter also beat Salem 59-56 in the Queen City Invitational Basketball Tournament in December.

“A lot of people didn’t even expect we’d be in this situation,” Londonderry coach Nate Stanton said. “I’m just proud of them. They’ve been resilient all year and turned us back into that winning culture at Londonderry. It’s the toughest group as a team I’ve had here in my six years.”

Londonderry (17-5) received a team-high 18 points from Max DesRosiers, who suffered a stress fracture in his foot when Exeter beat Londonderry 60-49 during the regular season. Jackson Cox added 13 points for the Lancers. Ethan May, arguably Londonderry’s top offensive player, was held to five points, but led his team with seven rebounds.

Exeter led 15-12 after one quarter and 31-21 at halftime. Morissette led all scorers in the half with 13 points. The Blue Hawks had a 15-point lead in the third quarter, but the Lancers used a 12-0 run to get back in the game and took a 38-37 lead on a DesRosiers jumper with 1:02 left in the third.

Londonderry trailed by six when it missed the front end of a 1-and-1 situation on consecutive possessions. A missed layup followed, which kept the Exeter lead at six points with 1:33 left.

Exeter played most of the game without starting forward Ethan Imbimbo, who suffered an ankle injury in the first half and remained on the bench throughout the second half.

“They worked, they came back and they didn’t roll over,” Stanton said. “We could of had them, but it was on us. We’ve never been in this situation. Never been in this atmosphere, but at the end of the day very proud of them. Heck of a season.”