Capitals left wing Alex Ovechkin stands during the national anthem before Game 1 of the Stanley Cup finals. (Toni L. Sandys/The Washington Post)

Here came a single Golden Knight, his plastic armor glowing beneath a yellow spotlight, his fake sword pointed at the ceiling, his eyes fixed on five red-caped skaters on the other end of the ice.

One of those red-caped skaters held a Washington Capitals flag, triggering one big boo from the dark stands, lit only by iPhones raised to capture whatever may happen next. The Golden Knight reached his fake sword to his real neck and mimed a slow slash, showing he was ready to slay his enemies, one by one. Not long after, computerized arrows rained down from a makeshift castle, shooting through the arena like camera flashes, and the red-caped skaters fell to the ice before scrambling off it.

There would be a hockey game inside T-Mobile Arena — at least eventually — but not before a performance fit for Las Vegas, if not so much a league known for its modesty. The improbable marriage of Vegas and hockey reached the NHL’s biggest stage Monday night, starting with one of the Golden Knights’ patented pregame shows and ending with their 6-4 win over the Capitals. The Golden Knights continued to be the league’s best attraction, heading into contests and during them, and they grabbed a 1-0 lead in the Stanley Cup finals as a result.

The 10-minute pregame show included a pounding drum line, a spirited battle scene and a movie trailer-like monologue that declared: “The Capitals from the East attack our fortress. And they are here.” The crowd responded with earsplitting chants of “Go! Knights! Go!” Michael Buffer — famous for saying “Let’s get ready to ruuummmblllle!” in a way no one else can — announced the starting lineups as if he were introducing heavyweight boxers at a nearby casino.

Then the lights turned on and a hockey game began.

“I was ready to rumble,” Golden Knights defenseman Nate Schmidt said, laughing, of Buffer bellowing his name before puck drop. “Now I know how Floyd [Mayweather Jr.] has felt all these years.”

“We feed off that energy,” forward Ryan Reaves said. “I think we’ve been feeding off that energy all year.”

That is how the Golden Knights climbed to 51 wins in their inaugural regular season, how they swept the Los Angeles Kings in the first round of the playoffs, how they beat the San Jose Sharks in six games in the second and then discarded the Winnipeg Jets in five in the Western Conference finals. Blazing starts. Relentless pushes into the offensive zone. Using the crowd’s pregame pulse to trampoline into games that, more often than not, end with them on top.

The players did not see the theatrics Monday. They never do. The Golden Knights are always going through their last bits of preparation and, even if they weren’t, the ice is occupied. But they felt the building shake as they sat in the locker room, the heavy bass vibrate the walls as they walked through the tunnel, the noise rise as they skated through a giant golden helmet and into an arena covered in laser beams and lingering smoke.

“Those guys are doing an unbelievable job,” Vegas forward Pierre-Edouard Bellemare said of the pregame performers. “And then it’s up to us to make sure that level of show keeps going.”

The Golden Knights did that at the start of Game 1, taking the first five shots before Colin Miller netted a power-play goal from the right faceoff circle at 7:15. The Capitals scored twice in 42 seconds later in the first period. Golden Knights center William Karlsson tied it less than three minutes after that, collecting a bouncing puck behind the Capitals’ net and wrapping it around and into the net.

The teams traded goals in the second before trading goals in the third before making it clear that the hockey would, somehow, match the dramatics of the pregame show.

“It was an emotional game for everybody,” Schmidt said. “I think fans got their money’s worth.”

Just before the midway point of the third period, Golden Knights defenseman Shea Theodore collected a failed Capitals clearing attempt and scanned the offensive zone. He spotted Tomas Nosek camped on the opposite post and zipped a pinpoint diagonal pass that Nosek whacked by Capitals goalie Braden Holtby to grab the late lead.

That gave the Golden Knights two goals from first-line forwards (Karlsson and Reilly Smith), two from their fourth line (Nosek and Reaves) and one from a defenseman (Miller). Nosek added an empty-net goal in the final seconds to punctuate the result.

That was pretty good theater in its own right, and fans left the arena having seen two stirring acts with the promise of much more. On Wednesday night, it will all unfold again.