BUFFALO, N.Y. — Islanders coach Barry Trotz wasn’t happy with how his team opened against a COVID-19-depleted Buffalo Sabres squad that hadn’t played in two weeks.

He was more pleased with his team’s finish in a 3-1 win on Monday night, in which the Islanders didn’t allow a shot on goal in the final period, a franchise first. And credit also went to goalie Semyon Varlamov, who stopped 20 shots, including all 12 he faced in the first period.

“I thought we would come out with a little more juice,” Trotz said after the Islanders extended their point streak to seven games (4-0-3).

“I knew they might be a little bit rusty, but they came out enthused,” he added, referring to the Sabres. “But I thought Varly was real strong for us.”

Varlamov provided the slow-starting Islanders a jolt with an instinctive save off Victor Olofsson’s one-timer from the lower right circle with five minutes left in the first period. Varlamov kicked out his left pad and got enough of the puck to have it bounce off the near post.

The Islanders responded with Anders Lee and Jean-Gabriel Pageau closing the period scoring goals 1:44 apart. Brock Nelson added a power-play goal in the second period, while Josh Bailey had two assists.

Mathew Barzal extended his career-best point streak to nine straight games (four goals, seven assists) by helping set up Lee’s game-opening goal.

Ultimately, the Sabres were undone by a lineup still missing six regulars, including three key defensemen, and the lingering affects of a coronavirus-forced break, which began two days after a 5-3 loss to New Jersey on Jan. 31.

Rather than use rust as an excuse, Sabres captain Jack Eichel blamed the loss on what he several times called sloppiness.

“We weren’t good enough. That’s what it comes down to in this league, you’re either good enough or you’re not,” Eichel said. “Obviously, we hadn’t played in the last two weeks. But nobody wants to sit here and make excuses.”

Buffalo had six games postponed and resumed practicing on Wednesday. The Sabres eventually had nine players land on the NHL’s COVID list, plus coach Ralph Krueger, who tested positive and said he experienced “moderately severe symptoms.” The 61-year-old returned to practice Sunday and was cleared to take his spot behind the bench on Monday.

Olofsson scored Buffalo’s lone goal, to extend his point streak to a career-best seven straight games, while Linus Ullmark was inconsistent in stopping 26 shots. Though Lee and Nelson scored by redirecting passes, Ullmark whiffed on Pageau’s shot, which came from a bad angle.

The inability to manage a shot on goal in the third period particularly stung. The closest the Sabres came to registering a shot happened with about four minutes remaining when Eric Staal crashed the net and appeared to have the puck deflect wide off his stick.

“It is what it is. It’s a bad period. It’s not a good period of hockey, not the way we want to play,” Sabres forward Kyle Okposo said. “But they’re a group that knows how to play well defensively, and they sucked us right in the third period, and we couldn’t dig ourselves out of a hole.”

It marked the fourth time in Sabres history they’ve failed to generate a shot on net in a period, and first time since a 4-1 loss to Anaheim in a 2011-12 season-opening game played at Helsinki, Finland.

The fewest shots the Islanders previously allowed in a period was one, with the most recent happening in a 6-3 loss at Washington on Jan. 28.

“We’d like to think in those situations we’re comfortable and we know what we need to do to lock things down, but you certainly can’t expect that to happen,” Bailey said of a third period in which the Islanders had a 12-0 edge in shots. “That’s just part of the commitment that we need to have the success that we’re looking for.”