Wyatt Johnston had two goals and an assist, Miro Heiskanen had a goal and two assists, and the Dallas Stars beat the Colorado Avalanche, 5-1, in Denver on Monday night to take a commanding lead in the Western Conference semifinal series.

Dallas leads the series 3-1 with a chance to close it out at home on Wednesday night. Sam Steel and Evgenii Dadonov also scored, Jason Robertson had two assists, and Jake Oettinger turned away 25 shots for the Stars.

"We've got some young guys playing big for us, really happy to see it again," Stars veteran Joe Pavelski said, speaking particularly of Johnston, who turns 21 on Tuesday. "Got us going with a big short-handed goal there. He was all over it tonight."

Dallas center Roope Hintz left the game early in the second period with an upper-body injury and didn't return.

Alexandar Georgiev made 29 saves, Casey Mittelstadt scored and Jonathan Drouin had an assist in his return to the lineup for Colorado. Drouin had been out since suffering a lower-body injury in the final game of the regular season.

After the game, Drouin explained the approach his team needs to take if it hopes to come back and take the series.

"It's just one game," the 10-year veteran said of where his focus sits. "Can't win two in the next game, it's about one game, make sure we're focused for Wednesday. We beat them there this year, we've beaten them in the playoffs, so we have confidence in that."

Likewise, Pavelski's view is that, despite the Stars' recent run of success, the series is far from over.

"We did our job. Played good hockey all around and got a lot of contributions," said Pavelski, who has one assist so far this postseason. "We know there's still a big job to be done, that's a really good group over there and they can get it going in a hurry."

Drouin's return was thought to give the Avalanche a full lineup but an hour before puck drop the NHLPA announced that Colorado forward Valeri Nichushkin has been placed in Stage 3 of the Player Assistance Program of the NHL/NHLPA and is suspended without pay for a minimum of six months.

Avalanche defenseman Devon Toews was also scratched due to illness.

"It's tough," Makar said of losing both Nichushkin and Toews. "You go home expecting both to play but it's unfortunate the way that it ended up. But at the same time we have a deep group, we get Drou back so there's a lot of confidence in the room. We've got to find ways to start better."

The Stars outshot Colorado 16-2 in the first period and got the only goal on a penalty kill. Johnston stole the puck from Cale Makar deep in the Avalanche zone and fed Steel in the slot for a wrister. Georgiev stopped that but Johnston knocked in the rebound at 15:37.

Johnston made it 2-0 with a power-play goal at 5:46 of the second period, his team-leading seventh goal of the postseason.

Heiskanen extended the lead to 3-0 at 11:24, his fourth goal, but Mittelstadt answered for the Avalanche at 12:35. It was his second of the playoffs.

That's all the hosts could manage against a stingy Stars defense, which has held Colorado to two goals in the last two games. The Avalanche were averaging five goals through their first seven postseason games.

Dadonov's goal at 9:27 of the third, his third of the playoffs, made it a three-goal game. Steel scored his first of the postseason into an empty net at 18:10.

Game 5 is Wednesday in Dallas (9:30 p.m. ET on ESPN).