Before the meeting, Colorado led 3-2 in matches and it initially looked like St Louis would succeed in getting a seventh match in the quarter-final series.
1-0 to the home team after the first period became 2-1 after the second.
But in the third, the guests put in an extra gear and after a draw plus that decisive goal in the closing seconds, St Louis had to thank for itself in this year's Stanley Cup.
-It's a sour way to end.
But that's the way it is.
Our guys fought hard, says St. Louis coach Craig Berube after the loss.
Colorado meets Edmonton in the semifinal series.
-They have played good hockey, it is a good team.
It will be a new challenge for us and we look forward to it, says Colorado's Josh Manson about the upcoming opposition.