Tampa Bay Lightning goaltender Andrei Vasilevskiy added to his glittering resume as he shut-out the Florida Panthers 2-0 in Game 4 of their series, locking up a 4-0 series sweep.

It marks the sixth time Vasilevskiy has shut-out an opponent in a series-clinching win – the most in NHL history.

He also became the first player since at least 1955-56, when saves first started being tracked, to save at least 30 shots, allow no more than one goal, and earn the win in five consecutive games. 

The Lightning outscored the Panthers 13-3 for the series.

In Monday's game, Tampa Bay's home fans had to wait until the third period for the deadlock to finally be broken, as Pat Maroon got on the end of a Zach Bogosian assist, before Ondrej Palat sealed things with an empty-net goal with the clock winding down.

Speaking to post-game media, Lightning coach Jon Cooper highlighted how silly it was to question the quality of an all-time goaltender like Vasilevskiy after a tough start to their last series against the Toronto Maple Leafs.

"I’m not so sure there’s much more I can say about [Vasilevskiy]," he said. 

"It’s funny how the playoffs are – five games into the Toronto series and you’re asking all these questions about what’s wrong with Vasilevsky.

"It's never a doubt in our locker room. A goalie's job, if you want to be elite, is to give your team a chance to win.

"When a goaltender gives your team a chance to win, it comes in a variety of ways. Tonight, it was that he wasn’t letting anything in. And we’ve seen that time and time again."

Tampa Bay's Alex Killorn added that it is a joy to take the ice next to a future Hall-of-Famer.

"It’s pretty cool to play with a player that I think will go down as one of the best goalies that’s ever played the game," he said. 

"That’s how you kind of gauge players – how they perform in big-time games – and he’s been nothing but tremendous in his game."

Panthers interim coach Andrew Brunette said while it was a tough pill to swallow, it was a tremendous learning experience for his side after winning their first playoff series since 1996 to earn a shot at the reigning back-to-back Stanley Cup winners.

"They’re really good – I mean, they’re Stanley Cup champions for a reason," he said.

"Their evolution of how they were once a high-flying, kind of offensive team, and [now] they've found their recipe on how to win, and they stick with it.

"Obviously, we aspire to be them, and this was another learning experience for us. We need to be better."

The Tampa Bay Lightning's Ross Colton admittedly could not believe his eyes when he scored the winning goal against the Florida Panthers in a 2-1 victory, to take a 2-0 lead in their playoff series.

Colton was called onto the ice with under a minute remaining in the third period and the score locked at 1-1, but abandoned caution and made his way towards the net as Nikita Kucherov retrieved the puck.

Kucherov found Colton as he approached the net with an astonishing backhand, no-look flick off the boards as the Panthers defence converged onto him, leaving Colton with the relatively simple finish to win the game.

Colton's look of near-bewilderment almost said as much but he confirmed his awe at the 28-year-old Russian's assist afterwards.

“I couldn’t believe he [Kucherov] got it on my stick,” Colton said. “I think when we went in the corner, I just said, ‘Are you kidding me?’ like 10 times because I honestly couldn’t believe he put it on my stick.

"When you’re on the ice with Kuch, you’ve got to be ready for anything. He’s got eyes in the back of his head, because I don’t even know how he could tell I was there."

The Lightning were relentless defensively against one of the NHL's best attacking teams this season, snuffing out four Panthers power plays, including one with under five minutes remaining.

While singling out Kucherov as a "special, special player", Lightning coach Jon Cooper asserted the defensive performance and ability to snatch games in clutch moments was a reflection of the team's character.

“No, I’m not surprised,” Cooper said. “I’m just surprised they waited until 3.8 seconds left to do it.”

In Thursday's other result, the St. Louis Blues evened up their series with the Colorado Avalanche, winning 4-1.

Goaltender Andrei Vasilevskiy was the hero as the Tampa Bay Lightning boosted their three-peat bid by winning 4-1 over the Florida Panthers in Game 1 in second round of the Stanley Cup playoffs.

The Lightning beat the Panthers in the first round of last year's playoffs 4-2 after going 2-0 up in the series and Tuesday's win got them halfway there in this year's Eastern Conference semi-finals.

Tampa Bay coach Jon Cooper was full of praise for 27-year-old Vasilevskiy, who made 34 saves as the Lightning fired in three third-period goals to get the win.

Vasilevskiy's 34 saves are the most he has had in a game this postseason, while he has stopped 94 of 99 shots over the past three games.

"Look at the saves he makes at the times we need them," said Cooper in his 124th playoff game with the Lightning.

"To me, that's what great goaltenders do and they give you a chance to win a hockey game and that’s what our guy did again tonight."

Nikita Kucherov, who scored a goal and had an assist, also hailed the Russian goaltender.

"He brings 100 per cent effort every single game and everybody's just trying to take his energy and bring it to your game," Kucherov said.

"He's a leader ... he's our best player."

Florida had taken the lead through Anthony Duclair in the first period but the Lightning hit back with four unanswered goals from Corey Perry, Pierre-Edouard Bellemare, Kucherov and Ross Colton to take the win.

"We're still learning and unfortunately we had to learn again tonight. We will be better next game," Florida interim coach Andrew Brunette said.

"They are too good of a team, a veteran team, and they're not going to open the door for you. We had our opportunities. On to the next game."

Florida Panthers interim coach Andrew Brunette said his side's fighting spirit was key in a series comeback against the Washington Capitals, culminating in Friday's 4-3 victory in overtime.

It was the Panthers' third straight win after falling down 2-1 in the series, and Game 6 was closely contested throughout.

After a scoreless first period, Nic Dowd opened the scoring for the Capitals, before Ryan Lomberg answered straight back to keep things at 1-1 heading into the last frame.

Nicklas Backstrom put the home side back in front, but the 'Comeback Cats' would not lay down, with Claude Giroux and Aleksander Barkov giving the Panthers a 3-2 lead.

In the closing stages, after the Capitals had pulled their goalie to get an extra attacker on the ice, T.J. Oshie found the equaliser to send the crowd into raptures and force overtime.

But this was the Panthers' night, and Carter Verhaeghe slotted the golden goal less than three minutes into the extra period to win the game and seal the series.

It is the first time the Panthers have won a playoff series since 1996, and Brunette said the performance epitomised their season.

"I think it's what we saw all year – the resiliency of the group," he said.

"People will say we're the 'Comeback Cats' – I'm not sure that's what I see – I see a group of guys that get hit, and they don't fall down, and they start hitting back. 

"They showed that throughout the whole series, they showed it tonight. 

"We gave up a late goal – it was a heart-breaking moment that could really affect you and can kill momentum – but again, we took the punch, we stood up, and we started punching back. It epitomises the whole season for us."

Asked if finally getting an elusive series win takes the pressure off his players, Brunette said he hopes it is the case.

"I hope [the series win takes the monkey off the Panthers' backs] – especially for the guys that have been here for a while," he said.

"It probably feels really good, because they put a lot of pressure on themselves – probably too much – throughout the course of the series. They were able to find a way and pull through it.

"I think as the series went on I felt they loosened up a little bit. We were a little nervous at home the other night, but they found their mojo and got going. 

"These things – you've got to go through them a few times to really get the feel of it. You have to have heartbreaks, you have to have things not go your way, to find out how hard it is, and understand it, and be resilient. 

"When you see the reward like they did tonight, it's all worth it."

The Florida Panthers twice came back from a one-goal deficit to defeat the Washington Capitals 3-2 in overtime, tying the series at 2-2.

Heading into the contest trailing 2-1, and playing on Washington's home ice, the Panthers were put on the back foot early after T.J. Oshie opened the scoring in the first period.

Carter Verhaeghe tied things up less than 10 minutes later, before Evgeny Kuznetsov put the Capitals back in front in the third period off an assist from legendary teammate Alex Ovechkin.

With just over two minutes to play, Sam Reinhart tied it at 2-2 to force an extra period, where Verhaeghe would slot the winner five minutes in to steal the game on the road.

Speaking to post-game media, two-goal hero Verhaeghe said the result adds to the belief of what this team – dubbed the 'Comeback Cats' – can accomplish.

"We wanted to come in and have our best game of the series, and I think we did a pretty good job," he said.

"It’s just kind of a building block. We know we have another level to get to, and we’re a great team, so I think it’s just building some confidence."

Fellow goal-scorer Reinhart added that the backs-to-the-wall nature of the battle was everything he enjoyed as a competitor.

"Those are the kind of situations you want to be in as a hockey player," he said. "It’s a game that can really go either way at the end of it – we stuck with it, and we’re happy with the result."

Washington's Ovechkin – a three-time Hart Memorial Trophy winner for league MVP – was clear about the next course of action, and not overreacting to a painful loss.

"At the end, it was bad bounces and it goes in," he said. "It is going to be a tough, long series, so move on. Forget about it, move on."

It was much smoother sailing for the Colorado Avalanche, beating the Nashville Predators 5-3 to sweep their series 4-0. J.T Compher and Cale Makar both collected a pair of assists each for the Avalanche.

The Pittsburgh Penguins received a vintage performance from future Hall-of-Famer Sydney Crosby as he slotted one goal and dished two assists in his side's 7-2 win against the New York Rangers, taking a 3-1 series lead in the process.

Lastly, the Calgary Flames won a crucial Game 4 on the road against the Dallas Stars 4-1 to tie their series at 2-2, despite Stars goaltender Jake Oettinger making 50 saves.

Pittsburgh Penguins captain Sidney Crosby was quick to back goaltender Louis Domingue, following their 5-2 loss to the New York Rangers on Thursday.

The Rangers tied their playoff series up at 1-1 after Pittsburgh's 4-3 win in triple-overtime at Madison Square Garden on Tuesday.

One of the key figures in that overtime win, Domingue was given a start by Penguins coach Mike Sullivan, but gave up key goals to Ryan Strome and Chris Keider via deflections.

Crosby backed his teammate following the loss, bringing saves he did make with Game 2 in the balance in perspective.

"The fourth was a bad bounce, a couple of tips there," Crosby said. "I thought he [Domingue] was solid. I thought he made some big saves, especially when there was a one or two-goal difference, that kept us in it."

The two-time Hart Memorial Trophy winner believes the Penguins simply need to start better and put three periods of hockey together to progress past the Rangers.

"It's the playoffs," Crosby said. "There are going to be swings of momentum but I thought that in both games, as they've gone on, we've probably gotten better. We just have to find a way to come out of the gates a bit better.

"You don't want to get down two, we've done that a couple of times now. It's not something we want to make a habit of.

"We get that late one and we had some really good chances early in the third and didn't convert, and they got a bounce. That's what it came down to."

In other NHL playoff results on Thursday, a Cale Makar goal gave the Colorado Avalanche a 2-1 overtime win over the Nashville Predators, moving to 2-0 in their series.

Meanwhile, the Dallas Stars and Florida Panthers tied up respective series with the Calgary Flames and Washington Capitals.

Evgeni Malkin says the Pittsburgh Penguins "deserved to win" after he scored the decisive goal 5:58 into the third overtime of their 4-3 victory over the New York Rangers in the NHL playoffs on Tuesday.

The Penguins take a 1-0 lead in their Stanley Cup playoff opening-round series, where goalies Igor Shesterkin and Louis Domingue were outstanding for both sides.

Penguins back-up goalie Domingue came in for Casey DeSmith who exited due to cramping. Domingue starred with 14 saves in the second overtime and three more in the third.

"We know we can win every game if we play right," Malkin told reporters. "We play smart. We play hard. I think we deserved to win tonight."

The Rangers had led 2-0 after Andrew Copp doubled their lead in the second lead after Adam Fox's power-play goal in the first period.

The Penguins leveled it up after goals from Jake Guentzel in the second period, before Chris Kreider restored the Rangers' lead. Malkin found Bryan Rust to square the game up again, before it headed for overtime. Malkin came up with the decisive deflection.

The epic was the longest-ever NHL game played at Madison Square Garden.

On Domingue, Malkin added: "For me, I know Louis is unbelievable. He is big and he is fast. I wasn’t worried. It is hard to score on him in practice."

Washington Capitals forward Tom Wilson was injured as his side won 4-2 over the Florida Panthers in Game 1 of their series. Wilson had scored before going off with a lower-body injury.

Colorado Avalanche piled on five first-period goals as they routed the Nashville Predators 7-2 in Game 1 of their first-round playoff series.

Elias Lindholm's first-period goal proved the difference as the Calgary Flames got past the Dallas Stars 1-0.

Colorado Avalanche Jacob MacDonald was alert and responsive after being taken off the ice on a stretcher following a hit from Ryan Lomberg in their win over the Florida Panthers on Sunday.

MacDonald was sent crashing to the ice by Lomberg in the second period, prompting an immediate stoppage in play and a fight between Lomberg and MacDonald's furious team-mate Nicolas Aube-Kubel.

A statement from the Avalanche shortly after said MacDonald had full movement following the second incident in less than a week that has seen an NHL player taken off on a stretcher.

Jujhar Khaira was also carried off in the Chicago Blackhawks' loss to the New York Rangers after a hit from Jacob Trouba.

"Scary moment, but apparently he's seen our trainers and everything's good," Colorado coach Jared Bednar said. "I think [the hit] might have been clean, yeah. I only got the one angle on it. They kept showing it over and over, and it looks clean from there.

"Physicality's part of the game. I don't like seeing guys go down, especially when they can't get up, but I don't think you can take it out of the game." 

Avalanche defenseman Erik Johnson added: "Just tough to see from probably either team. It's a fast game out there, you move upwards of 20 mph. It's physical and things move fast.

"It's an unfortunate play, super scary for Jacob. It's tough, you just never want to see that and hopefully he's OK. 

"That's the stuff that makes you sick to your stomach when it happens to any team-mate or opponent.

"Unfortunately those hits are still part of our game. ... What is that now, two in a week that you've seen guys stretchered off? That's not good for our game."