The Merrimack High School boys hockey team had Saturday’s Division II quarterfinal against Dover won twice.

But a bounce here and a bounce there, and instead of moving on to the final four for the third time in four years, the No. 7 Tomahawks saw their season come to an end.

Up 2-1 in the final minute of the third period, Merrimack’s Ryan Downie missed an empty net that would have iced the win. Then, No. 2 Dover dug the puck out of the corner and Griffin Guerra tapped it past goalie Devin Gillis with 9.9 seconds remaining to force overtime.

Kieran Lombard netted the game-winner for Dover 4:27 into the extra session, beating Gillis on a two-on-one to give the Green Wave a 3-2 win at the Dover Ice Arena.

Dover moves on to the semifinals Wednesday at Concord’s Everett Arena against either No. 3 Bow or No. 6 Goffstown.

“I thought our guys showed up, ready to go,” Merrimack coach Kurt Mithoefer said. “It was one of the best games I’ve seen them play.”

Merrimack (11-9) got two power-play goals from Mark Feeney, the first of which came just 34 seconds in, and for more than two periods, it looked like those goals were going to be enough.

The early goal, which went in off a Dover defenseman, seemed to deflate the Green Wave to the point that coach Steve Riker wondered if his team could score.

“The first two periods were not good for us,” Riker said. “I stood on the bench wondering how we were even going to score a goal in this game. We had nothing.”

But then Dover got a jolt in the worst way. Early in the third, with Merrimack on a three-on-one rush, the Green Wave’s Ben Henderson collided with a teammate at the other end and was knocked out. Play was stopped for about 10 minutes while an ambulance was called and Henderson was taken off on a stretcher.

Henderson was communicating and moving his limbs after the hit, and Dover rallied around its teammate, getting a goal from Mitchell Welch less than a minute later.

“You never want to see a kid get taken out in an ambulance, but that gave them the life they wanted, to play for him,” Mithoefer said. “We were kind of in hang-on mode. We weren’t in sit-back mode, but we didn’t need another goal. The third one would have been huge and certainly, we’re not sitting back and allowing them to attack.”

When Merrimack took a timeout with 1:16 left, Dover elected to pull goalie Luc Ravenelle (23 saves), and just seconds later, Downie had the puck at the red line and open ice in front of him. But with a Dover player closing quickly, Downie took a shot from just outside the blue line and missed wide to the left.

“This could be it, no question,” Riker said. “You roll the dice there at the end.”

With time about to expire, Dover was able to get the puck out of the corner to the left of Gillis (27 saves) and Guerra’s shot as he was going from the goalie’s left to right got in moments before the goal was dislodged.

“I was telling the guys to get it down the ice and on that last one, our defenseman thought he had it eaten up in the corner and it popped out,” Mithoefer said. “I told the boys in between (third period and overtime) that we needed to match their intensity off the bat, and we did in the beginning. There was a breakdown, they got the two-on-one and it went in.”