LAS VEGAS -- It had to happen eventually.
The Vegas Golden Knights lost for the first time in the Stanley Cup Playoffs after winning the first five postseason games in their history, an NHL first.
[RELATED: Complete Golden Knights vs. Sharks series coverage]
They knew they weren't going to win 16 consecutive playoff games, but it took a power-play goal by San Jose Sharks forward Logan Couture 5:13 into the second overtime to defeat the Golden Knights 4-3 in Game 2 of the Western Conference Second Round at T-Mobile Arena on Saturday.
This was a game the Golden Knights thought they had won in the first overtime.
Jonathan Marchessault looked to have won it at 16:58 but his goal was overturned on video review when it was determined he interfered with Sharks goaltender Martin Jones.
Coach Gerard Gallant didn't blame the loss on the disallowed goal. He was more upset with how the Golden Knights, who are usually so dogged and determined, had an off night.
"They better be ready because we didn't show up for 45 minutes tonight. We didn't play our game tonight," Gallant said. "We played a great game the other night [a 7-0 win in Game 1] and competed and battled. Tonight, whether we thought it was going to be easy -- or what we thought, I don't know -- but we didn't show up to play our game tonight, and it cost us big-time.
"They were the better team all night. We had a good first overtime period, where we played really well, but we weren't prepared to play tonight."
Video: Situation Room: Marchessault's goal overturned
The best-of-7 series is tied 1-1. Game 3 is at San Jose on Monday (10 p.m. ET; NBCSN, CBC, TVAS).
"A lot of emotions," Vegas forward James Neal said about trying to regain focus after the disallowed goal. "It takes the wind out of your sails a little bit, I'd say. I thought we did a good job regrouping and getting back into it."
Neal had several chances to win it before the overturned goal.
"[David Perron] made a great play to me, a couple of times from behind the net," Neal said. "[One shot] hit [Jones' stick] knob and I thought it was going in. Oh, that was a tough one. I thought it was going in. But it hit the knob and it was a tough bounce, and then the wraparound [that slid through the crease].
"I had a few chances, for sure. I wish I would have buried them. Would like to have it back maybe."
Golden Knights goaltender Marc-Andre Fleury has been around long enough to know that though the loss may sting, they can't afford to let it linger.
"I think I've lost every way possible," Fleury said. "It's just another one. It doesn't matter if you lose 1-0, right, or if you lose in the second overtime. A playoff loss is a loss. You've just got to be able to put it behind you and move on for the next one."
Compared to Game 1, the Sharks were a far more resilient opponent. They won the special teams battle, going 2-for-7 with the man advantage, including Couture's winner, while the Golden Knights were 0-for-2. They also scored two second-period goals -- Couture's first and Brent Burns' second -- in 4-on-4 situations.
"I just don't like the penalties when we're taking them and going down 4-on-4 for no reason," Gallant said. "A lot of the penalties, you lose some rhythm, both teams, you lose rhythm."
He dismissed the notion the Golden Knights were overconfident.
"The last game meant nothing, and I've said it for two days," Gallant said. "There's no momentum. It's game-to-game in the playoffs. You're playing against a really good team. We know they're going to come out and play a strong game. We didn't play our game. We weren't fast. We weren't quick. We were lethargic most of the night, and that's on us."
Video: Couture lifts Sharks to 2OT win in Game 2
Stanley Cup Playoffs Round 2 Coverage
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Golden Knights vs. Sharks