LAS VEGAS -- The Vegas Golden Knights are going to the semifinals for the third time in four years -- not bad for a team that has been around for only four years.

Vegas knocked out the Colorado Avalanche with a 6-3 win in Game 6 on Thursday, its fourth straight win to pull off the series comeback.

"I don't think there was a person in the hockey world, when we were down 2-0, that thought we would finish this in Game 6 at home tonight," Golden Knights coach Pete DeBoer said. "That was real. A lot of talk about us being swept, being embarrassed, could we even win a game? We have a group with a lot of pride. They blocked out the noise and went to work."

After losing the first two games of the series, including a 7-1 rout in Game 1, Vegas reeled off four straight wins. In doing so, the Golden Knights handed the Avs their first four-game losing streak of the season.

Colorado, which edged out Vegas for the Presidents' Trophy as the NHL's top regular-season team, has lost in the second round for three straight years.

"I'm going into my ninth year next year and haven't won s---," Avalanche star Nathan MacKinnon said. "I'm definitely motivated. It just sucks."

The Golden Knights, on the other hand, are enjoying the spoils as they continue to rewrite expectations for an expansion franchise.

"It's so hard to get to this point," DeBoer said. "Everybody talks about winning the Stanley Cup, but I'm an Ontario guy. I've watched the Toronto Maple Leafs closely, I was drafted by the franchise. They haven't gotten out of the first round in, what, 17 years now? And that's a good franchise: well run, well coached. It's hard to make the playoffs in this league, it's hard to win a series. So what these men have accomplished, it's unreal."

But Vegas has set its sights much higher.

"We have built a winning mentality, we built a winning franchise, but at the point we're at right now -- we're in Year 4, and we need to start winning Cups," winger Jonathan Marchessault told ESPN on Wednesday. "I mean, yeah, it's fine we made the playoffs four years in a row, but a Cup would be the only thing to bring us satisfaction."

In the pivotal Game 6, Vegas had six goal scorers, including defenseman Alex Pietrangelo, who broke a tie late in the second period for his first goal of the postseason. Pietrangelo had taken a team-high 45 shots during the postseason before he finally got one past Avalanche goaltender Philipp Grubauer. DeBoer called Pietrangelo "the best player in the series, on either team."

The Golden Knights also won because their top line of Mark Stone, Max Pacioretty and Chandler Stephenson effectively stifled Colorado's star-studded top line, featuring MacKinnon, Mikko Rantanen and Gabriel Landeskog, from Game 3 on. By Game 5, Avalanche coach Jared Bednar was forced to break up his top line, hoping to find a spark.

"They're Presidents' Trophies winners, one of the best lines in hockey, one of the best players in hockey," Stone said. "They have a Vezina candidate, a Norris candidate, an MVP candidate. That's a good team we just eliminated."

The Golden Knights welcomed a full-capacity crowd of 18,000-plus, which DeBoer cited as a catalyst for the comeback.

"The advantage of the full rink in Game 3, 4 and 6, huge to our group," DeBoer said. "If we don't have full capacity and the rink isn't rocking for all of those games, I'm sure we're playing a Game 7 on Saturday night."

Instead, Vegas faces the Montreal Canadiens in the semifinals, marking the first time this season a United States-based team will play a team in Canada. The series also pits Pacioretty against the Canadiens, the team he formerly captained. Pacioretty was traded to the Golden Knights in 2018 for a package that included Nick Suzuki, now one of Montreal's ascending young players.

If Vegas wins its next series, it will advance to the Stanley Cup Final, which it also did in its inaugural season.

"It's pretty impressive," Pietrangelo said. "It's a winning culture that was built here since the first year. Different guys have come in, but the culture stayed."