The Stars lead the best-of-7 series 3-2. Game 6 will be in Denver on Thursday.

Mikko Rantanen had a goal and two assists, and Roope Hintz had a goal and an assist for Dallas, which is the No. 2 seed from the Central Division. Jake Oettinger made 26 saves.

Nathan MacKinnon had a goal and an assist, and Martin Necas had two assists for Colorado, which is the No. 3 seed from the Central. Mackenzie Blackwood allowed five goals on 18 shots before being replaced at the start of the third period by Scott Wedgewood, who made eight saves.

Johnston gave the Stars a 1-0 lead nine seconds into the first. Off the opening face-off, he chased down a dump-in to the right of the net and scored with a sharp-angled shot that deflected in off the side of Blackwood.

The goal is tied for the fifth-fastest to begin a game in Stanley Cup Playoff history.

Thomas Harley made it 2-0 at 19:15. His shot from the high slot was stopped by the blocker of Blackwood, but the rebound popped into the air and landed on the goalie’s back before rolling into the net.

Rantanen extended the lead to 3-0 with his first goal of the series at 1:12 of the second period. He finished off a pass from Hintz on a 2-on-1.

Artturi Lehkonen cut the lead to 3-1 at 12:11 when he deflected Necas’ one-timer from the top of the crease.

MacKinnon made it 3-2 at 14:38. He warded off Matt Duchene at the point before scoring with a shot from the high slot that beat Oettinger blocker side.

Johnston responded for Dallas to make it 4-2 at 16:48. He one-timed a cross-slot pass from Duchene from the bottom of the right circle for a power-play goal.

Mason Marchment extended the lead to 5-2 at 18:32 when he deflected Alexander Petrovic’s shot from the right point.

Hintz scored into an empty net at 17:55 of the third period for the 6-2 final.