It was the 401st career victory for Fleury, who moved into a tie with Chris Osgood for 12th on the NHL all-time victories list. It was also the fourth shutout of the season for Fleury as the Golden Knights improved to 17-3-2 against Pacific Division opponents.
Karlsson, who also had a hat trick in a 6-3 victory over Toronto on Dec. 31, has 39 goals. That ranks second in the Western Conference behind Winnipeg's Patrik Laine, who has netted 41.
Colin Miller also scored for the Golden Knights (46-21-5, 97 points), who increased their lead in the Pacific Division to eight points over the San Jose Sharks while also snapping a four-game home losing streak.
Mike Smith stopped 27 shots for Calgary (35-28-10, 80 points), which lost its second straight game and fell for the third time in four games.
Fleury was brilliant while registering 20 saves during a scoreless first period, the most shots by an opponent at T-Mobile Arena this season. The Golden Knights then exploded for four goals in the second period, including two in the span of 53 seconds early in the period while taking a 2-0 lead.
Miller scored the first on a power-play when his shot from the high slot deflected off Flames' defenseman Michael Stone's arm in front of the net and dipped down past Smith's stick for his 10th goal of the season.
Karlsson then followed with the first natural hat trick in team history, scoring three goals in the span of nine minutes and 16 seconds. The first came on a one-timer over Smith's glove off a crossing pass from James Neal.
The second was off of a pass from behind the net by Jonathan Marchessault that glanced off Smith's glove. The last came at the end of a 2-on-1 with defenseman Nate Schmidt that ended with a wrist shot just inside the post on Smith's stick side.
--Field Level Media
Calgary | Vegas | |
N/A | Points | William Karlsson 3 |
N/A | Goals | William Karlsson 3 |
N/A | Assists | Nate Schmidt 2 |
N/A | Power Play Goals | Colin Miller 1 |
N/A | Short Handed Goals | N/A |
Mike Smith .871 | Save Percentage | Marc-Andre Fleury 1.000 |
Mike Smith 27 | Saves | Marc-Andre Fleury 42 |
Team | Shots | Goals | Power Play | Penalty Kill | Penalty Mins | Face Offs Won |
Calgary | 42 | 0 | 0-2 | 1-2 | 8 | 24 |
Vegas | 31 | 4 | 1-2 | 2-2 | 8 | 31 |