NORTH ANDOVER, Mass. – When you are averaging exactly one goal a game during a five-game stretch, your margin of error is reduced dramatically. Any mistake or missed opportunity can prove costly.

So when an airborne puck was misplayed by University of Maine junior goalie Ben Bishop and Merrimack College center Rob Ricci deposited it into the vacated net midway through the third period Saturday night, it resulted in a 2-1 Warrior victory.

It was Merrimack’s first-ever weekend sweep of the Bears as the Warriors had won Friday night’s affair 5-1.

The Warriors, 3-27-4 a year ago, improved to 6-4-1 overall, 3-4-1 in Hockey East.

Maine’s fourth straight loss extended its winless streak to five games (0-4-1) and the Bears fell to 4-6-1 and 2-4-1.

It is Maine’s worst 11-game start since the 1985-86 season (1-10).

The five goals tie a school record set last season for fewest goals in a five-game span.

Sophomore right wing Matt Jones opened the scoring 7:19 into the game with his sixth goal in his last seven games but Maine junior Matt Duffy, playing in just his second game at right wing after moving up from defense, answered just 2:17 later.

Bishop and Merrimack’s Patrick Watson turned in stellar performances and their teams played well defensively.

Maine’s David de Kastrozza was whistled for hooking at the 9:26 mark of the third period and Ricci converted on the power play.

The puck popped high in the air and Bishop skated out of his net to his left to try to snare it.

But when he went to grab it, it hit his glove and landed on the stick of Ricci, who was eight feet away from the goalie.

“There were about eight guys in front. But the bottom half of the net was open,” said Ricci, who slid it home.

“That was 100 percent my fault,” said Bishop. “I thought I had it. I’ll make that play [successfully] 99 times out of 100.”

Maine had a power-play opportunity when Joe Loprieno was called for charging with 4:04 remaining.

The Bears moved the puck well but never got a shot on net as the Warriors blocked some shots and kept them to the perimeter.

Andrew Sweetland had the best opportunity when he teed up a one-timer from the left circle but John Jamieson slid out to smother it.

Maine’s anemic power play, 0-for-3 on the evening without a shot on goal, has fallen to a 5.9 percent success rate. The Bears are 1-for-23 with the man advantage over the last six games.

“We had our chances. But we’ve got to shoot more. We’re passing up opportunities to shoot and it’s killing us,” said Maine senior defenseman Bret Tyler, who quarterbacks one of the power-play units. “You can’t score if you don’t shoot.”

Merrimack finished with 17 blocked shots on the evening and outshot Maine 25-23.

“The guys did a great job in front of me,” said Watson, who had 11 Grade-A (high-percentage) saves among his 22. “They blocked shots, they let me see most of the shots and they cleared the front of the net so I could tie up any rebounds.”

“Merrimack had a great weekend. They deserved [the sweep],” said Maine coach Tim Whitehead. “They played as a team and they outplayed us. They blocked a lot of shots and they kept the front of their net clear.

“At the end, they converted on their power play and we didn’t. That was the difference,” added Whitehead. ‘We’ve got to find ways to score goals.”

The Maine coach also praised Ricci for his faceoff success (he won 24 of 37).

“We tried everyone against him,” said Whitehead.

“I take pride in my faceoffs,” said Ricci, who also had an assist on Jones’ goal.

Ricci got the puck back to Pat Bowen and the defenseman’s shot deflected over to an unattended Jones, who was behind Bishop to the goalie’s left.

“He had an open net,” said Bishop, who finished with 12 Grade-A stops among his 23.

Duffy tied it directly off a Glenn Belmore faceoff win in the circle to Watson’s right.

Duffy’s screened wrister cleanly beat Watson to the far corner over Watson’s glove.

Merrimack coach Mark Dennehy said his team did a thorough job on Maine’s top line of Keenan Hopson between Billy Ryan and Sweetland, who mustered just three shots on goal between them.

“The guys didn’t let them get behind them,” said Dennehy.

Watson made two clutch saves in the waning moments as he closed his pads on a tricky one-timer by Belmore in the middle of the high slot and squared his body up to absorb a Sweetland tip off a Ryan shot in his chest.

Maine was without centers Wes Clark (shoulder injury) and Tanner House (six-game suspension) and right wing Vince Laise (stomach injury).

WARRIORS 2, BLACK BEARS 1

Maine (4-6-1) 1 0 0 – 1

Merrimack (6-4-1) 1 0 1 – 2

First period – 1. Mmk, Jones 7 (Bowen, Ricci), 7:19; 2. Maine, Duffy 1 (Belmore), 9:36. Penalties: Mmk, Farrell, high-sticking, 1:11; Maine, Hopson, hooking, 3:01.

Second period – No scoring. Penalties: Maine, de Kastrozza, cross-checking, 8:07; Mmk, Jones, tripping, 8:49.

Third period – 3. Mmk, Ricci 4 (unassisted), 9:59 (pp). Penalties: Maine, de Kastrozza, hooking, 9:26; Mmk, Loprieno, charging, 15:56.

Shots on goal: Maine 6-9-8-23; Mmk 9-9-7-25

Goaltenders: Maine, Bishop (25 shots-23 saves), Mmk, Watson (23-22)

Power-play opportunities: Maine 0-3, Mmk 1-3

High-percentage scoring chances: Maine 6-6-6-18; Mmk 8-6-6-22

Attendance: 2,312