Alex Pietrangelo and Alex Tuch also scored goals, while Marc-Andre Fleury made 33 saves as the Golden Knights extended their winning streak to six games, matching a season best.
Stone had his fourth consecutive multi-point game, matching his career best, previously done Dec. 13 to 19, 2019.
Currently on a three-game COVID-19-related pause, the Avalanche are not scheduled to return to action until Thursday at St. Louis. The Golden Knights and Avalanche are scheduled to meet two more times in the regular season.
“These are important points as we are trying to hunt down Colorado, stay in the mix and make sure we are relevant in that race,” Vegas coach Peter DeBoer said. “We needed to win all these (six) games in order to do that and I think the guys knew that and they are coming out and getting the job done.”
Max Comtois and Danton Heinen scored goals for Anaheim, while Adam Henrique reached 200 assists in his career. John Gibson made 24 saves for the Ducks.
Pacioretty gave the Golden Knights a quick 1-0 lead at 3:25 of the first period when he redirected Alec Martinez’s shot from near the blue line past Gibson. It was Pacioretty’s team-leading 22nd goal, while Stone had a secondary assist, his team-leading 35th.
After they were held without a goal in a 4-0 loss to the Golden Knights on Friday, the Ducks finally got on the scoreboard when Comtois scored at 6:23 of the opening period, his team-leading 13th and his third in his past seven games.
Vegas went on top for good when Pietrangelo scored at 14:46 of the first period when he brought the puck in across the blue line and took advantage of a sagging defense when he blasted a shot just inside the left post. It was his fourth of the season.
The Golden Knights made it 3-1 when Roy scored at 2:43 of the second period, his fifth of the season.
“I think it was a full team effort tonight again and we are playing with a lot of confidence,” Roy said. “It’s not many games now until the playoffs and we just have to keep going in the same way.”
After Heinen ripped a shot past Fleury from near the right boards to pull Anaheim within a goal, Stone made it a two-score advantage when he delivered his 15th of the season with 1:47 remaining in the second period.
“We came here (Friday) and obviously the first game was, start to finish, pretty dominant,” Stone said. “This one was a tougher game to play. We thought they would come out with more urgency and they did. (Fleury) kept us in there over the first five minutes. … That has been the key these last games, we’re getting leads and sticking to them.”
Henrique’s 200th assist came on Heinen’s goal, with 65 of those assists coming in his four seasons with the Ducks.
Tuch scored an empty-net goal for Vegas with 1:27 to play, his 16th. Martinez had a pair of assists for the Golden Knights.
“I’ve got a great amount of respect for that hockey club over there, how they’re built, how they play, their experience, their skill level and their work ethic,” Ducks coach Dallas Eakins said of the Golden Knights. “They are a well-oiled machine and that is a pretty good blueprint of where we need to go.”
GOLDEN AGAINST THE DUCKS
Sunday’s victory gave Vegas a 6-1-0 record against Anaheim this season, continuing a dominating history. The Golden Knights have won 16 of their 19 games against the Ducks, their most regular-season victories against a single team.
One more game remains in the season series, back at Anaheim on Saturday.
MAKING HIS MARK
Roy has become more assertive from his center position of late, anchoring the Golden Knights’ fourth line Sunday while scoring in back-to-back games against the Ducks.
Of Roy’s five goals, four have come in his past seven games. It was the first time Roy had scored a goal in back-to-back games in his 76-game career.
“I thought at the start of the season, when you don’t get the bounces, you get good chances but they don’t go in, you end up playing with less confidence or in your head a little bit,” Roy said. “Lately I have been lucky that the same bounces went in. I am playing with a lot more confidence now.”
Golden Knights: A set of back-to-back games at home against the San Jose Sharks will begin Monday, ahead of a return visit to Anaheim on Saturday.
Ducks: A visit to face the Los Angeles Kings on Tuesday will be the first of five games between the area rivals in a span of 12 days.