Moore tied the game 2-2 at 6:18 of the second period. Matt Roy's shot from the blue line hit Golden Knights forward Alex Tuch before going in off Moore's stick.
"We take a punch or two to the face, and then we get ourselves off the mat, we continue to battle," McLellan said. "And now that's in our game, that's in our DNA. That's a moral victory. I think we're a better team than we played tonight. I think we showed 'em a little too much respect and disrespected what we're capable of doing."
Pacioretty gave the Golden Knights a 1-0 lead on a one-timer off a pass from Stone at 10:17 and scored with a backhand to make it 2-0 at 12:53. Video review determined Quick caught the puck over the goal line for the second goal.
"We got back to the bench, a couple guys mentioned that you could tell on video," Pacioretty said. "Every angle I saw, I couldn't tell, but they were pretty adamant about it. That being said, I didn't want them to jinx it."
Iafallo chipped in the rebound of Anze Kopitar's shot with 18 seconds left in the first to cut it to 2-1.
"We talked about it before the game, it's definitely a big game for us," Iafallo said of playing Vegas. "We got to win those ones. I feel like we had some good moments, but we had some bad moments that we've got to fix tomorrow, and we just have to go from there and stay positive."
The teams will complete a two-game set here Sunday.
NOTES: Stone had two goals and eight assists in a four-game point streak March 1-6 before missing a 2-0 loss to the Minnesota Wild on March 8 with an undisclosed injury. He has four goals and four assists during his current six-game point streak. … Defenseman Shea Theodore had an assist on Pacioretty's second goal to extend his point streak to six games (two goals, seven assists). … Iafallo has four points (two goals, two assists) during a personal four-game point streak, including a goal and two assists in the past three since he missed a 2-0 loss at the Colorado Avalanche on March 12 because he was ill. … The Kings used 11 forwards and seven defensemen. McLellan said it was a coach's decision and not based on player availability.