The Golden Knights were 500-1 betting underdogs to win the Stanley Cup to begin the season and are now just one victory away from advancing to the Stanley Cup finals.
Jets goalie Connor Hellebuyck stopped 26 shots.
"I was just sitting there and people, they were fighting", Fleury said, "and (I was) trying to have a little smile by myself".
"We win that game nine times out of 10", Winnipeg winger Blake Wheeler said.
Patrick Laine and Tyler Myers countered for the Jets, who lost their third in a row this series. Their surprisingly successful inaugural season is still rolling along, and they're one victory from a berth to the Stanley Cup final.
The St. Louis Blues were among six teams that joined the NHL in 1967 - doubling the league to a dozen teams - when they were swept in the final by the Montreal Canadiens. I think the Jets are prepared for it and us fans are too.
Jonathan Marchessault scored 35 seconds into Game 3 and it was the left-winger from Cap-Rouge, Que., who set up the first goal less than three minutes after puck drop Friday.
The Jets took over where they left off in the third period of Game 3 by outskating the Golden Knights in the first period of Game 4, but Karlsson's power-play goal was the difference.
"Absolutely we should (have the cup come to our street)", De La Torre said with a laugh.
Friday was a must-win game for the Jets because National Hockey League teams that take a 3-1 series lead have gone on to win the series more than 90 percent of the time. "We've been scoring big goals after that". Winnipeg just won a Game 7 on the road against the Nashville Predators to reach the conference final, so it won't be intimidated on the road in an elimination game on Sunday.
Marchessault added an empty-net goal with 3 seconds left, becoming the first player in league history to score in the first and last 60 seconds of the same Stanley Cup playoff game, according to the NHL. Then, it was Hellebuyck failing to secure a shot by Pierre-Edouard Bellemare, who raced to the puck and fed Nosek, who punched it in to put Vegas up 2-1.
First, it was Laine's one-timer on the power play that even Fleury wasn't catching up to, and it tied the game at the 9:29 mark.
Scheifele had five shots Friday but failed get one past Fleury.
Czech forward Nosek redeemed himself by coming out of the box and banging one home from in close to restore the Knights' lead at 2-1.
With Myers serving an interference penalty Karlsson beat Hellebuyck low glove side on a cross-ice feed from Marchessaault at 2:25.