Pittsburgh Penguins\' Ryan Malone, bottom, is knocked off his skates by New York Rangers\' Michal Rozsival, of the Czech Republic, in the third period of the hockey game in Pittsburgh, Saturday. (AP Photo/Keith Srakocic)
Maxime Talbot made a good play to keep the puck in the zone and got the puck to Armstrong, who took a wrist shot from the right boards that deflected off Rangers defenceman Marek Malik's stick and squeezed between goalie Henrik Lundqvist and the near post.
Armstrong's 10th goal of the season came after Sidney Crosby tied the game 2-2 with 13:04 to play in regulation to record his 100th point of the season.
Evgeni Malkin added a goal and an assist for the Penguins, who have played in four consecutive games that were decided after the end of regulation. Heading into the contest, Pittsburgh had played in four shootouts in five games - winning three, including March 1 against the Rangers.
Karel Rachunek and Matt Cullen scored for the Rangers, who have earned at least a point in each of their past six.
Crosby, who does not turn 20 until August 7, scored while on a power play three minutes after the Penguins cut the lead to 2-1.
Crosby was standing to the right of Lundqvist when he gloved a Malkin shot that was wide of the net. He set the puck down and smacked it behind Lundqvist for his 28th goal of the season.
Crosby, who later hit the post while on a power play with less than four minutes to play, also has 72 assists in 65 games this season after posting 39 goals and 63 assists for 102 points in becoming the youngest player to record at least 100 points in a season last year.
The Rangers had been 21-3-4 when leading after two periods but blew their second two-goal, third-period lead to Pittsburgh in 10 days and missed an opportunity to move into a tie for eighth place in the Eastern Conference.
Rachunek scored the game's first goal with 45 seconds to play in the opening period. Michael Nylander passed from the right win to Rachunek, who slapped a one-timer for his sixth goal of the season.
Cullen gave the Rangers a 2-0 lead 1:11 into the second after what looked like a soft wrist shot from just inside the blue-line snuck past Penguins goalie Marc-Andre Fleury for his 13th goal.
The Penguins began their comeback when Malkin cut the New York lead to 2-1 with a power-play goal 3:32 into the third period. Taking a pass from Ryan Whitney while above the right face-off circle, Malkin hesitated before firing a slapshot - using Rachunek as a screen - past Lundqvist.
The Penguins have come-from-behind in each of their past five victories.
The game attracted the 16th sellout in the Penguins' past 18 home games. The team announced Monday it was aggressively pursuing relocation after this season if plans for a new Pittsburgh arena are not finalized soon.
Notes: Rangers C Ryan Hollweg took 14 shifts for 8:50 of ice time two days after taking a vicious hit to the face by the stick of the Islanders' Chris Simon. Simon is suspended indefinitely for the incident. . . . RW Georges Laraque took part in his first fight as a Penguin, squaring off against New York RW Colton Orr midway through the first period. Laraque, one of the league's renowned tough guys, hadn't fought in his first five games since being acquired in a trade from Phoenix. . . . Prucha has a point in three consecutive games.