DiPietro bounced back from a pair of concussions to stop 32 shots in his first game in three weeks, and Marc-Andre Bergeron scored the go-ahead goal eight minutes into the third period to lead the Islanders to a 3-2 win over the top-seeded Buffalo Sabres on Saturday night.
Trent Hunter and Bruno Gervais also scored, helping New York tie the best-of-seven, first-round series at one, with Game 3 on Long Island on Monday.
The Sabres started sloppy, allowing New York to take a 2-0 lead 11 minutes in, and at times looked nothing like the efficient team that produced a 4-1 win in the series opener Thursday and the NHL's top record this season.
Defencemen Toni Lydman and Dmitri Kalinin scored for the Sabres, who finished the regular season with a league-leading 53 wins and 308 goals.
The Islanders seemed to be hanging on before Bergeron scored a power-play goal with 11:23 left - and six minutes after Kalinin tied the game during a scramble in front.
Bergeron's goal came on the Islanders' first shot of the period, when his slap shot from the right point beat Ryan Miller. New York forward Ryan Smyth contributed by providing traffic in front to distract the Sabres goalie.
DiPietro proved to be the difference, playing his first game since March 25, when he sustained his second concussion in a span of 12 days. He missed the final seven regular-season games and the opener against Buffalo.
The 25-year-old goalie made numerous key stops and provided the Islanders' renewed confidence to take more chances on offence.
"I felt good," DiPietro said. "I thought the team did a tremendous job in helping me see the puck in the first period."
He foiled Brian Campbell's shot from the slot with 6:44 left. DiPietro showed he was on his game from the start. Besides getting his shoulder on Lydman's hard shot in the opening minute, DiPietro's best save came when, while lying on the ice, he reached back to foil Thomas Vanek's backhander from in close.
New York defenceman Tom Poti added two assists.
The Sabres started out playing flat, while the Islanders opened with a newfound sense of urgency. New York went up 2-0 when Gervais' shot from inside the blue line somehow sneaked through Miller's legs.
The Islanders' 16 shots in the first period nearly matched the 21 they managed in Game 1, and were far better than the one soft shot they produced in the first period Thursday.
"It was nice," DiPietro said. "We did a lot of the things we talked about."
Lydman cut the lead to 2-1 late in the first period when his shot from the high slot deflected in off Poti. Kalinin then tied it 2:12 into the third, when he converted a rebound after DiPietro stopped his initial shot and denied Daniel Briere.
Notes: Sabres co-captain Chris Drury played in his 100th career post-season game, and 20th with Buffalo. Drury played his first 80 with Colorado, including in 2001 when he helped the Avalanche win the Stanley Cup. ... Sabres LW Ales Kotalik was demoted to the fourth line in the second period, replaced by rookie Drew Stafford, who took his spot alongside Drury and Dainius Zubrus. ... Islanders G Wade Dubielewicz, who stopped 31 shots in his career playoff debut Thursday, served as DiPietro's backup, replacing Mike Dunham. ... The Islanders snapped a five-game losing streak - including regular season - at Buffalo. Their last win was Feb. 27, 2004.