Colorado Avalanche players were thrilled for center Darren Helm after he scored the series-winning goal in his side's 3-2 victory against the St. Louis Blues with just five seconds remaining in regulation.

With their Game 6 triumph away from home, the Avalanche secured a 4-2 series win, and will now play the Edmonton Oilers in the Western Conference Finals, with the winner earning a chance at the Stanley Cup.

It was far from a comfortable win for the Avalanche, needing to come from behind twice.

Firstly, after Justin Faulk gave the Blues a lead in the first period, Colorado's J.T. Compher equalised five minutes into the second frame.

That tie would last less than five minutes before Jordan Kyrou got on the end of a build-up by Andre Burakovsky and Josh Manson, making it 2-1 for the home side, and that score would hold through the second period and the first 10 minutes of the last.

After a penalty gave the Avalanche a power play, Compher capitalised with his second goal of the game, tying things up with just under 10 minutes to play.

With both teams pushing for a late winner, it would be the away side to produce the breakthrough, as Helm found his way past Blues goaltender Ville Husso in the dying seconds to deliver the series win to the Avalanche.

Speaking to post-game media, Avalanche forward Gabriel Landeskog said it was a joy to see Helm be the hero, scoring his first goal of the postseason when his team needed it most.

"There's no other guy that deserves it as much as he does," he said. 

"You talk about his work ethic, but he's the guy that comes to the rink with a smile on his face, gets along with everybody."

Colorado goaltender Darcy Kuemper shared similar sentiments, calling it "a super-clutch goal".

He added: "It's always fun to see someone like Darren, who plays the game so hard, (but) always doesn't get rewarded with the points – to come up with a big goal like that is really special."

Avalanche coach Jared Bednar said he could tell from the jump his side was up for the challenge, and that there is still plenty of work to do.

"From the drop of the puck, we were ready to go," he said. "You could tell the belief was there."

"We're only halfway to our goal... we're just getting started."

The Blues were left licking their wounds, convinced they side were good enough, but just failed the test.

"We feel like we're a good team and we let that series slip," Blues center Brayden Schenn said.

St. Louis coach Craig Berube added: "It's tough, a tough way to end it. That's the way it goes. Our guys battle hard."

Game-winner Tyler Bozak said the St. Louis Blues were not ready to go on holidays after they pulled off a stunning 5-4 comeback in overtime against the Colorado Avalanche to keep their season alive.

With the win, the Blues still trail 3-2 in the series, but they earned a chance to head home to St. Louis for Game 6

The Avalanche looked all set to move on to the next round after a pair of first period goals to Nathan MacKinnon, and a second-round strike from Gabriel Landeskog had them up 3-0 at the halfway point.

Instead of lying down, the Blues fought back in front of the raucous Avalanche crowd, with Vladimir Tarasenko pegging one back to make it 3-1 at the end of the second period.

The Avalanche were able to hold things together for the first nine minutes of the last period, until the Blues' pressure started to pay off, with Robert Thomas trimming the margin to 3-2.

Jordan Kyrou would have thought his goal would send the game to overtime as he made it 3-3 with less than five minutes to play, but the Avalanche answered straight back as MacKinnon finished off his hat-trick with under three minutes on the clock.

But there would be another twist to the tale, as Thomas was able to force home his second goal, the equaliser, with 56 seconds remaining in regulation.

Overtime only lasted 3:38 before Bozak silenced the home fans with the golden goal to keep the Blues' Stanley Cup dreams alive.

Speaking to post-game media after scoring the winner, Bozak said his side was not ready for things to end this way.

"Just a resilient group of guys," he said. "[We] got down, [but] didn't want the season to be over.

"[We] fought hard and got some big goals late. I just got a little bounce up top and saw a lane to the net. 

"In overtime, there's definitely no such thing as a bad shot. I just tried to get it through on the traffic – all I know is that it went in, and that's all that matters."

Blues coach Craig Berube highlighted the gutsy effort to come from behind twice.

"We battle back, and then we give up that goal," he said. "It could have been deflating, but our guys have a lot of guts.

"Guys battled and kept battling. That's really what it boils down to. 

"We didn't get off to the start we wanted, being down quick. I thought the second half of the second period we started to come with our game.

"Getting to the goal line, winning battles down there. We went north. That's what it boils down to."

Thomas had not scored in any of the Blues' first 10 playoff games, but said it was nice to break the drought.

"Better late than never, I guess," he said.

"You've got nothing to lose – you might as well throw it all out there. That was the mindset."

Nazem Kadri scored a decisive hat-trick for the Colorado Avalanche against the St. Louis Blues in Game 4, having been determined to perform after alleging threats and racist abuse.

Avalanche center Kadri was involved in a collision with Jordan Binnington in Game 3, bringing a premature end to the Blues goaltender's series.

Former NHL player Akim Aliu revealed on Twitter on Sunday he had subsequently spoken to Kadri, who he said had "been subject to so many racist attacks and threats since last night that police had to be brought in".

The Avalanche confirmed they were aware of threats made towards their player – a Muslim of Lebanese descent – and were working with local law enforcement to investigate.

In the meantime, Kadri responded on the ice with three goals in Monday's 6-3 win to put the Avalanche 3-1 up and on the brink of the Western Conference Finals.

"I wanted to come out tonight and really put a mark on this game, especially after what happened," Kadri said. "I tried to do that as best as possible.

"Sometimes you've got to be patient, and you've got to wait. I was able to strike early in the second period and was able to get the mojo going."

He added of the incidents: "People need to be aware this stuff still happens, and it's hurtful."

Speaking ahead of Game 4, Blues coach Craig Berube – who had questioned Kadri's role in Binnington's injury, referencing his "reputation" in an apparent nod to previous postseason suspensions – said of the threats: "I've got no comment on that stuff."

St. Louis Blues coach Craig Berube sent a veiled shot at Nazem Kadri, after the Colorado Avalanche defeated his team 5-2 to take Game 3 in their playoff series.

Kadri bowled over Blues starting goaltender Jordan Binnington less than seven minutes into the first period, forcing him to leave the game with a lower-body injury.

Binnington, who made three saves in as many attempts to that point, was replaced by Ville Husso, who stopped 19 of 23 shots.

Berube did not overtly blame Kadri for the collision following the defeat, but made reference to his notoriously frenetic and aggressive style.

"Look at Kadri's reputation," Beurbe said post-game. "That's all I've got to say.

"There are a lot of calls you can question. That's hockey. I'm not going to sit here and talk about calls, that weren't called or called, it's just not worth it.

"I can be disappointed but talking about it is not going to change it."

The Western Conference's first seed took a 2-1 series lead on the back of a Artturi Lehkonen brace and 29 saves from Darcy Kuemper.

Kadri, Logan O'Connor and Gabriel Landeskog also scored for the Avalanche, who bounced back from a 4-1 loss on their home ice on Thursday.

Auston Matthews says his game-winner was "pretty special" after the Toronto Maple Leafs battled back from two goals down to win 4-3 over the Tampa Bay Lightning in the NHL playoffs on Tuesday.

The Maple Leafs trailed 2-0 after the first period but rallied with Matthews settling the contest with their third goal in the third period.

The win means Toronto lead 3-2 in the best-of-seven series against the reigning Stanley Cup champions.

"It was pretty special," Matthews told reporters, speaking about the goal. "To battle back from down two goals, and never losing hope and competing, that was big."

Matthews led the NHL across the regular season with 60 goals but he had not scored in the playoffs since Game 1 of the series.

Teammate John Tavares, who pulled one back during the second-period power play, praised the NHL's back-to-back Rocket Richard Trophy winner Matthews, who was also credited with seven hits.

"His whole game is all just really good," Tavares said. "When you score 60 goals, that's going to get [discussed], and how he scores it in different ways and the uniqueness of his shot in his abilities, but his all-around game is as good as anybody's in the league.

"He's going to play hard and compete because they're making it hard on him to earn his ice and opportunities, so good for him to play them hard."

The victory means Toronto are one win away from the franchise's first playoff series victory since 2004.

"I just think we needed to possess the puck a little bit more," Matthews said. "Get on top of them and be forechecking and not giving them as much time and space. We were on top of them and had our heads up to make plays."

Elsewhere, Adrian Kempe's over-time goal earned the Los Angeles Kings a 5-4 win over the Edmonton Oilers, having blown a 3-1 lead.

The goal was Kempe's second of the game, as he finished with a three-point performance. The result puts the Kings up 3-2 in the series.

The Carolina Hurricanes also moved up 3-2 in their series against the Boston Bruins with an emphatic 5-1 win after losing their past two.

Rookie Seth Jarvis scored twice and Antti Raanta finished with 34 saves.

The St Louis Blues piled on three third-period goals, all from a Vladimir Tarasenko hat-trick, to secure a 5-2 win over the Minnesota Wild to lead their series 3-2.

Tony DeAngelo saved special praise for rookie goaltender Pyotr Kochetkov after the Carolina Hurricanes defeated the Boston Bruins 5-2 on Wednesday.

Kochetkov was thrust into the spotlight for his playoff debut as the Hurricanes took a 2-0 lead in what is becoming a fiery series.

With Frederik Andersen already down, tempers boiled over as the Canes had to turn to Kochetkov after Antti Raanta was struck in the head by David Pastrnak's glove as he skated past.

The two teams traded words and big hits throughout, and defenseman DeAngelo made it clear where the Hurricanes stand with the Bruins in this series.

"We're not going to get pushed around, I guarantee you that," he said.

DeAngelo was glowing of Kochetkov's demeanour after the first-period change and his ability to keep it simple in a heated environment, making 30 saves.

"I think he's real calm," his team-mate said. "You don't see any jitters, at least in my eyes. I don't know what he's feeling inside. I'm sure he's a little nervous. Anybody would be, right?

"But I thought he was real calm in the net. He made a lot of saves, wasn't trying to do too much. He was calm. Coming into goal in the first period in a playoff game as a rookie after coming here a few weeks ago, he was really good."

Elsewhere on Wednesday, the Tampa Bay Lightning and the Minnesota Wild tied up their respective series against the Toronto Maple Leafs and the St. Louis Blues with wins.

The Edmonton Oilers also tied up their series, smashing the Los Angeles Kings in a 6-0 shutout.

Composure was the key to the St Louis Blues stunning three-goal comeback after defeating back-to-back champions Tampa Bay Lightning 4-3 in a shootout win in the NHL on Tuesday.

The Blues trailed 3-0 at 5:29 in the opening period as Erik Cernak and Corey Perry scored five seconds apart for the Lightning.

St Louis rallied with two second period goals while Jordan Binnington made 30 saves and was perfect in the shootout.

Blues scorer Ryan O'Reilly told reporters: "The coaching staff was positive with us and had a good message of just sticking with it and build it up and knowing that there's a lot of game left. That's exactly what we did.

"I thought everyone did a good job at not being fazed. It's not what we wanted but it's a long game."

Blues coach Craig Berube said: "You've got to feel what's going on in the game. You've got to stay composed. I just told our team there's a lot of hockey, stay with it. we've got to get one back. Get some momentum going."

The Lightning had a chance to win the game in over-time after Blues forward Jordan Kyrou's penalty but could not clinch it.

"We went to overtime, we had our chances, but we didn't get it done," Lightning coach Job Cooper said. "We were a tired group at the end there."

Like everything else over the past year, the hockey world has been turned upside down by the coronavirus pandemic. The 2019-20 season was completed with teams playing in bubble locations in Toronto and Edmonton and the 2020 campaign will open without fans as part of a condensed 56-game season, among a slew of other changes. 

With the previous season extending several months past the normal ending date, the league had little choice but to delay the start of 2021 and to find a way to make a shortened season work. The new plan is for the regular season to end on May 8, with the Stanley Cup awarded no later than July 9. 

Of course, nothing is set in stone anymore and the NBA and NFL have had to deal with countless COVID-19 issues, so the NHL expects similar problems to arise with the pandemic experiencing another surge. The league knows it may have to adapt and games will very likely need to be rescheduled. 

The NHL has already dealt with this, as the start of the season for the Dallas Stars had to be pushed back to January 19 after six players and two staffers tested positive for coronavirus. While the completion of last season in the bubble locations was virtually flawless, teams are playing in home arenas this season, increasing the chances of players becoming infected. 

To combat this, teams will be allowed to carry taxi squads of four to six extra players who will practice and be prepared to step in when needed. 

While there is less hockey to enjoy, there are some tweaks to the upcoming season that fans will enjoy. 

The four divisions have been realigned and they include an all-Canada division of seven teams, made necessary by border restrictions. The other three divisions are mostly based on geography, but St Louis and Minnesota were shuffled into a division with the three California teams, Vegas, Arizona and Colorado. 

The Chicago-Detroit rivalry gets renewed with the Red Wings moving into the Central Division, and Tampa Bay and Dallas – last season's Stanley Cup Final participants – are now together in the Central.  

There should be no shortage of intensity this season with teams scheduled to play mostly back-to-back sets solely against teams in their own division. So, the Flyers and Penguins will meet eight times, as will the Islanders and Rangers and Kings and Ducks. The teams in the all-Canada division will face each other nine or 10 times.  

The first two playoff rounds will be played within the division, meaning the bad blood that started in the regular season could grow even deeper. The division winners will then advance to the semifinals but seeding will be based on points rather than geography.  

The new setup raises the possibility of a Stanley Cup Final between traditional East teams like the Capitals and Penguins or Canadian rivals Montreal and Toronto.   

To recoup some of the money lost by having no fans or limited fans at the start of the season in some cities, the NHL is allowing teams to include a sponsor name on their helmets and each division will also include the name of a corporate sponsor. 

The condensed season was preceded by an abbreviated training camp without exhibition games and there is concern that the start of the season will be marred by sloppy play. This could be especially true for the seven teams that have not played a game since March after they did not qualify for the expanded playoffs.  

As in any offseason, several big-name players changed teams. It will be jarring to see 43-year-old Zdeno Chara in a Capitals uniform and Joe Thornton playing for the Maple Leafs after 14 seasons in San Jose. Henrik Lundqvist would have looked strange as a member of the Capitals following an 887-game run with the Rangers, but he decided not to play this season due to a heart condition. 

Injuries will also keep some marquee players off the ice for a while. Lightning forward Nikita Kucherov – the 2018-19 scoring leader – will miss the entire regular season due to hip surgery and the Stars could be without top forward Tyler Sequin (hip) and goaltender Ben Bishop (knee) until at least March.  

Blackhawks captain Jonathan Toews is out indefinitely with an unknown illness and there is no word on whether the 12-time 20-goal scorer will play this season. 

While this season is full of unknowns and will be like no other before it, the potential is there for it to be one of the most exciting in recent memory.