CHICAGO -- The Vegas Golden Knights became the first Stanley Cup champions to open the following season 6-0-0 with a 5-3 win against the Chicago Blackhawks at United Center on Saturday.

Nicolas Roy broke a 2-2 tie 13 seconds into the third period.

“We just wanted to play a better third [period],” Vegas coach Bruce Cassidy said. “We knew we weren’t at our best for the first two periods. We had pockets of good hockey, pockets where we were fighting the puck, lost our structure at times. So we just wanted to have a good period. Yes, it helps.”

Connor Bedard, the No. 1 pick in the 2023 NHL Draft, scored his second NHL goal 90 seconds into his first home game for the Blackhawks (2-4-0). Arvid Soderblom made 19 saves.

VGK@CHI: Bedard opens scoring with PPG

Paul Cotter had a goal and an assist for the Golden Knights, who passed the 1920-21 Ottawa Senators and 1985-86 Edmonton Oilers for best start by a Cup champion. Adin Hill made 21 saves.

“It’s cool,” Hill said of the start. “We came in with the mentality of trying to repeat what we did last year. I think it’s carried over. The last couple of [preseason] games, we started getting a little smoother and a little more crisp with things, just to implement our system. I think we carried that through into the season, and it’s been pretty seamless. It’s been a good start, so yeah, keep building on it.”

Bedard made it 1-0 at 1:30 of the first period on the power play. Off the face-off, a wide-open Bedard took a pass in the slot from Taylor Hall and put a wrist shot past Hill. It was Bedard’s second goal of the season, and it came after he was held scoreless in his previous two games.

”It's always nice to score,” he said. “Whether it was first career goal or first goal here, it's always nice to get that, and it feels good to get it quick. It was big for our power play to see one go in, but obviously now it doesn't feel as good, but in the moment, it was great for sure. You can remember it, for sure, when you're looking back on it. But obviously now, you're focused on what we can do better to win. But obviously, as a moment in your life, looking back you'll remember it.

“It was electric in there. It was cool for me and all the guys there. You get energy from that. For us to get one early and get [the fans] up like that was great. They're awesome, so it was a lot of fun to play in front of them.”

William Karlsson tied it 1-1 at 4:05 on a backhand shot on the power play, picking up the rebound of a shot by Cotter from the edge of the left circle.

VGK@CHI: Karlsson ties the game at 1-1 with a PPG

Jonathan Marchessault put Vegas ahead 2-1 at 7:30 of the second period. He moved into the slot, and his wrist shot got between Soderblom’s pads.

Chicago tied it 2-2 at 8:50 when Reese Johnson deflected Connor Murphy’s point shot past Hill.

Roy gave the Golden Knights the 3-2 lead 13 seconds into the third period, taking a backhand pass on the rush from Keegan Kolesar and scoring from in front of the net.

“For sure, I think that was a bit of a killer for them,” Karlsson said. “If you let one in right off the bat, that’s going to give us momentum.”

Mark Stone scored at 13:47 for a 4-2 Vegas lead, putting the puck in after Michael Amadio circled the net and fed it out in front. Cotter scored on the power play at 16:09 to make it 5-2.

VGK@CHI: Stone finishes Amadio's feed in front

Corey Perry scored from the right circle for Chicago for the 5-3 final at 19:45.

Bedard’s power-play goal was the lone goal on the man-advantage for the Blackhawks, whose power play is 2-for-27 in the first six games.

“I thought the end of the second period we had some really good opportunities there,” Blackhawks coach Luke Richardson said. “Unfortunately [they] didn’t go in. ‘AA’ (Andreas Athanasiou) had one on the back door, Tyler (Johnson) had one in the slot. I think we hit the post again tonight on that. So we’ve just got to keep shooting. I’d still like to see quicker movement, more shot mentality. I think at times we had it, and at times when it doesn’t go in, they want the perfect play which, you have to go with works.

“We’ll keep driving that home and hopefully they fall.”

NOTES: Vegas defenseman Alex Pietrangelo (upper-body injury) has skated the past two days. Cassidy said he hopes Pietrangelo “rejoins the group” for practice Monday. … The Blackhawks had a pregame video tribute to late owner Rocky Wirtz, who died July 25 at 70 … Bedard (18 years, 96 days) became the second-youngest player in Blackhawks history to score in their home opener behind Eddie Olczyk (18 years, 56 days on Oct. 11, 1984). The only other teenagers to do so for Chicago were Stan Mikita (19 years, 140 days on Oct. 7, 1959) and John Harms (19 years, 187 days on Oct. 29, 1944).