LAS VEGAS (KLAS) — Six games in, and the Golden Knights are still looking to play a complete game.

“I think our consistency, a full 60 minutes, it needs to be better,” wing Jonathan Marchessault said Saturday after he and his teammates fell 3-2 to the defending Stanley Cup champion Colorado Avalanche at T-Mobile Arena.

Avalanche goaltender Alexandar Georgiev (40) makes one of his 33 saves as teammate J.T. Compher (37) slides across the crease to help. (AP Photo/Chase Stevens)

Marchessault, who scored his team-leading fifth goal on a power play in the opening period, echoed the feelings of his teammates after the somewhat frustrating loss.

Captain Mark Stone, who assisted on both Knights’ goals, once again referred to the overall effort as a work in progress. He thought the difference was two failed power plays — he called them “a little slopppy” — at the start of the third period with his team trailing 2-1.

“Had some quality chances. We just got to find a way to even that game,” he said. “Overall, I didn’t think it was terrible. Maybe a little bit of panic, kind of watching them skate around early on.”

Stone was pointing to the opening period, dominated by the Avs (3-2-1). For the Knights (4-2), who have jumped to early leads in most of their games, the effort, especially at home and against a team on the second night of a back to back, was a bit surprising.

But goaltender Logan Thompson, who was solid again, made nine saves, several of them on good scoring chances, and the Knights slowly started to respond.

“I think the second period we were better as a group,” Marchessault said. “And we played well in the third period. … But our start, our discipline, and they had two goals on the power play. It makes a difference at the end of the night.”

Coach Bruce Cassidy said he saw stronger play after a wonky opening period, and he wasn’t totally disappointed with the power play. There were chances, good ones, he said. But like Marchessault and Stone, Cassidy noted the difference was two power-play goals by Colorado and one by his team.

Colorado, which is 9-for-17 on the power play, tops in the NHL, converted both its chances Saturday. The Knights were 1-for-4 with the man advantage and are 4-for-23 after six games.

“The power play was functioning,” Cassidy said. “The disappointing part was the third period. Again, when you really need it. Timely goals, right. Happened a little bit in Calgary (3-2 loss), where theirs was a little better than ours.”

One of the Knights’ best chances with the man advantage came on a mad scramble in the third-period, but goaltender Alexandar Georgiev, who had 33 saves, sprawled across the crease and covered the puck at the side of the net with his blocker.

Perhaps because of momentum from the power play or maybe a tiring opponent, the Knights had a 14-5 shot advantage in the third. But a superb end-to-end rush by Valeri Nichushkin gave the Avs a 3-1 lead at 8:12.

Nichushkin took the puck from the right faceoff circle in his own zone, zipped past Phil Kessel’s poke check in the neutral zone and then wide past defenseman Brayden McNabb to go backhand-forehand over Thompson’s glove and into the top corner. It was his sixth goal and 11th point.

“Obviously, huge goal, huge individual effort,” said Avs coach Jared Bednar, who also praised his players’ overall effort, calling it a more complete game. “Loved their start.”

Cassidy’s reaction was a tad different. An uneven effort, even with the passionate late surge, left him lamenting his team’s opening period.

“You look at that first period, it seems like we were watching them a lot,” he said.