Watch: Matt Duchene's 2OT winner sends Stars to conference final

Duchene had also been involved in what at first looked like the game winner earlier.

Mason Marchment appeared to win it for the Stars with 7:29 left in the first overtime period with a shot from the high slot off a faceoff. 

But it was immediately ruled no goal on the ice because of contact with Georgiev. Duchene was battling for position with Colorado defenseman Cale Makar near the crease, and it was ruled that Duchene interfered with Georgiev.

The call stood after a review.

Duchene was also foiled on a breakaway chance early in the second OT.

Stars goalie Jake Oettinger was spectacular with 29 saves.

Dallas coach Pete DeBoer shuffled his lines after the second intermission, and one of the new combinations was Tyler Seguin centering captain Jamie Benn and Evgenii Dadonov. It paid off when Benn tied it 1-1 for the Stars 1:56 into the third period. 

He took a backhand pass from Dadonov in the slot on the rush, made a move and slid a backhand shot past Georgiev. Seguin got the second assist.

It was Benn's third goal of the postseason but his second marker and fifth point of the series.

Mikko Rantanen's power-play goal 5:48 into second period gave the Avalanche a 1-0 lead. He beat Stars goalie Jake Oettinger high on the short side with a snap shot from bottom of the right circle.

It was his fourth goal of the playoffs, but the star winger had managed only four points in the first five games of the series.