A pair of Islanders victories in two days only turned up the heat even more.
Anders Lee scored the go-ahead goal early in the third period, Jaroslav Halak made 27 saves, and the Islanders beat the Pittsburgh Penguins 4-1 on Saturday night to sweep a home-and-home series.
Lee's third goal of the season at 2:38 came on a tip-in of Lubomir Visnovsky's slap shot that got past backup goalie Thomas Greiss. Brock Nelson added a power-play goal at 9:47 -- his team-leading 10th tally -- and Islanders captain John Tavares closed the scoring with his eighth of the season at 15:46.
"Our execution was really good, we are playing the right way," Tavares said after the Islanders won for the eighth time in nine games.
New York had tied it 1-1 in the second period on a goal by Matt Martin.
The Islanders and Penguins -- heated rivals since they met in the 2013 playoffs -- played to a 5-4 shootout victory by New York on Friday.
"Certainly the rivalry is right up there with the Rangers," added Tavares, who scored for the second time in eight games. "It's exciting for us and for our fans."
The resurgent Islanders (14-6), who finished last in the Metropolitan Division last season, saw Halak win his sixth straight start. The veteran who joined New York as a free agent last summer has allowed just eight goals in those games.
"We made high percentage plays and did a good job of matching their speed," Islanders coach Jack Capuano said. "We managed the puck well, and we played a smart game."
New York tied Pittsburgh atop the division with 28 points, though the Penguins (13-4-2) have played one fewer game.
"We didn't have a good third period, and they raised their game," Penguins captain Sidney Crosby said. "They were more intense than we were in the back-to-back."
Fans at Nassau Coliseum chanted "First place, first place" in the closing minutes. The Islanders are off to their best start since the 1987-88 season.
"The atmosphere was incredible," Capuano said. "We played the Islander way."
The Penguins had won seven of eight on Long Island.
Evgeni Malkin gave the Penguins a 1-0 lead with his eighth goal 16:49 in when his shot was stopped by Halak but dribbled into the net. Malkin's new linemates -- Patrick Hornqvist and Nick Spaling -- assisted. Both were acquired in a trade with Nashville last summer.
Martin's second goal of the season and second in two nights came as the Islanders' fourth line continued to contribute strong minutes. Casey Cizikas and Cal Clutterbuck had assists on the goal at 18:01 of the second.
The 25-year-old Martin played in his 300th NHL game.
"We're a group that really pulls for each other," Martin said. "To hear the crowd behind us like that adds a lot to our confidence."
Saturday's rematch had less offense but was spirited and hard-hitting. Steve Downie fought Travis Hamonic of the Islanders at 15:24 of the first.
In the second, the teams traded chances and had multiple crease skirmishes. The Islanders held a 22-16 shots advantage.
"All we do after this one is forget it," Crosby said.
NOTES: The Islanders honored Hall of Fame goalie Billy Smith before the game. Smith was an original Islander and played on all four Stanley Cup-winning teams from 1980-83. ... Forward Craig Adams played in his 900th NHL game for the Penguins. ... The Islanders are 12-1 when they score at least three goals (including shootout winners).