The Boston Bruins (35-22-6) collapsed on Sunday night in Pittsburgh, falling by a score of 5-4 in overtime after blowing a 3-0 lead, along with a late 4-3 lead in the third period.
It's Boston's seventh-straight road defeat (0-3-4) while simultaneously riding a 12-game winning streak at home.
The Pittsburgh Penguins (32-17-14) found a way to win without superstars Sidney Crosby and Evgeni Malkin, both of whom did not play.
Anthony Mantha scored twice in the third period, both tying goals. His first tied the game 3-3, then his second tied it at 4-4 with under nine minutes to play in the third.
Tommy Novak won it for the Penguins just 17 seconds into overtime, as the Penguins leapfrogged the New York Islanders for second place in the Metropolitan Division in the process.
For Boston, it was a colossal failure. Pavel Zacha's second hat trick of the season was not enough for the Bruins. For a team that had only lost three prior games when leading after two periods all season, this game was a total shock to the senses.
Joonas Korpisalo started brilliantly, then couldn't find the clutch save when Boston needed one. He allowed four goals on 14 shots in the third period and overtime in the loss.
But it'd be tough to hang much on Korpisalo. The Bruins could not cover the center of the ice nearly enough in the third, with their defensive structure becoming abnormally leaky.
Getting a point out of the game is a decent consolation, as it helps them gain ground on the playoff cut line. But in a game where Boston led 3-0, it's one they've got to win.
They're next in action Tuesday night back home, when the Bruins host the Los Angeles Kings as they look for a 13th-straight home victory.