"Sometimes you have to look at the big picture," Islanders coach Barry Trotz said. "We've had some guys out, we've had all that, but when it mattered we found ways to win."
Anthony Beauvillier broke a tie in the third period to help the Islanders sweep the home-and-home series. New York won 5-4 in a shootout on Tuesday.
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Valtteri Filppula scored twice for the Islanders (39-21-7), who share the division lead with the Washington Capitals. Thomas Greiss made 35 saves for his seventh win in his past 11 games.
"I've been switching them all year; I feel very comfortable with Robin [Lehner] in, and I feel very comfortable with Thomas in," Trotz said. "That's been a blessing for us this year. It's one of the reasons that we're in a position to be in the playoffs if we can continue to find ways to win."
Brady Tkachuk and Oscar Lindberg scored, and Anders Nilsson made 27 saves for the Senators (23-39-6), who lost for the ninth time in 10 games (1-8-1).
"I thought that was probably one of our most complete efforts in terms of time and in terms of players," Senators defenseman Mark Borowiecki said. "I don't think we had any passengers out there tonight. We were working hard, did a lot of good things, got beat by a good hockey club."
Beauvillier jammed in a loose puck at the side of the net to make it 3-2 with 7:31 remaining in the third period.
"I thought [Beauvillier] was really good on that line tonight," Trotz said. "Him and Michael [Dal Colle] and [Mathew Barzal], they had some [offensive] zone time. They haven't been able to find the back of the net the last little while, so it was good for them."
Casey Cizikas scored into an empty net to make it 4-2 with 49 seconds left.
Filppula scored with a backhand shot from the slot to give the Islanders a 1-0 lead at 5:44 of the first period.
