Victory was less than 20 seconds away.
The Ducks were furiously defending and their penalty-killers getting tested, five on three, and were within 19.5 seconds from establishing a near-lock on this playoff series on Tuesday night.
Unfortunately, for the Ducks, there are two third-period comeback teams in this series. Calgary tied Game 3 with 19.5 seconds left in regulation on the power play with rookie forward Johnny Gaudreau's first goal of the series and won it when forward Mikael Backlund scored through traffic at 4:24 in overtime.
At the end, the score line: Flames 4, Ducks 3.
The Flames secured their first victory in this Western Conference semifinal, cutting the Ducks' lead to two games to one. Game 4 is here on Friday.
“It's 2-1. We weren't planning on winning 16 straight games here,” Ducks forward Andrew Cogliano said. “We knew it was going to be a tough series, a tough battle.”
Ducks goalie Frederik Andersen was more succinct, saying, “It definitely sucks, that's for sure.”
He was talking about the Ducks losing their first playoff game after winning six straight.
Backlund's goal came on a delayed penalty and the Flames were able to get an extra attacker on with the goalie pulled. Andersen said it was a good shot through traffic, going past him on his right side and tough to pick up with all the bodies in front of him.
“It's unbelievable,” said Backlund, who scored his first career playoff goal. “It's hard to describe.”
Said Flames Coach Bob Hartley: “There's no words anymore to talk about this group. They never quit. They keep believing … we kept our composure.”
He called it a “great show of character, a great show of grit.”
Said Ducks Coach Bruce Boudreau: “We did an adequate job until the last 20 seconds. That guy [Gaudreau] has got a great shot. We let him in a position that he loves to be in and he's pretty accurate with it.”
On the overtime goal, the Ducks' Ryan Kesler looked like he thought he had touched the puck earlier on the play, meaning that the whistle should have been blown and the play stopped.
“It became helter skelter and once we were getting the penalty and they got the extra guy on, it was at the end of our shift,” Boudreau said. “I think our guys were tired and we stopped skating. We just sort of stayed in the same position and they scored.
“It looked like Kesler thought he touched it … I don't know if he did or he didn't. But the way he reacted. He obviously felt he did something with it.”
That quick ending couldn't possibly convey what was a spirited and controversial game. Gaudreau got the game to overtime, taking the puck along the right-wing side and skating into the circle. With the Ducks backing off ever so slightly, Gaudreau, a left-handed shot, launched a wrist shot and beat Andersen short side.
Until then, the crowd at Scotiabank Saddledome had been buzzing about the controversy earlier in the third period.
The burning question loomed: Did the puck completely cross the line?
The Flames thought that rookie forward Sam Bennett had tied the score with 6:17 game remaining. There was no call of a goal on the ice but the play was immediately reviewed by the NHL's situation room, leading to a lengthy wait.
It appeared as though Andersen had made the stellar save with his right leg, keeping the puck from crossing the line. Finally, there was the ruling. The situation room asserted that there was no conclusive evidence that the puck had completely crossed the line.
Follow Lisa Dillman on Twitter @reallisa