This was an opportunity wasted for the Cavaliers, a chance to strike first and put the Warriors in an early hole to start the NBA Finals.

This was the kind of game you have to win if you want to unseat and upset the reigning NBA champions. The Cavaliers may still come back and do that, but if they don’t, this could be the game that haunts LeBron James, his teammates and all of Northeast Ohio this summer.

Steph Curry missed 11-of-15 shots and Klay Thompson eight-of-12. The best backcourt in the NBA combined for a season-low 20 points and the Warriors still won Game 1 of the Finals going away, 104-89, Thursday night at Oracle Arena.

Ouch.

James, Kyrie Irving and Kevin Love all had productive if not big offensive nights — totaling 66 points — and the Cavaliers were still run off the floor in the final 14 minutes. It was the Warriors’ bench that did most of the damage. Onetime Net Shaun Livingston scored 20, matching Curry and Thompson combined, and leading the 45-10 bench scoring advantage.

“You don’t win championships without the entire squad coming in and making an impact on games,” Curry said.

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You can’t expect that kind of differential every night, otherwise it will be a sweep. But Game 1 will make many mouths on TV, radio or around your office say this series is over already.

Curry finished with 11 points and Thompson nine. On many nights, that’s a good quarter for those two. If Cleveland can’t beat the Warriors on a night that the Splash Brothers had trouble throwing it in the San Francisco Bay, what will the Cavaliers do when Curry and Thompson are on?

It’s too soon to bury James and the Cavaliers. It’s only one game, and the Cavs will make adjustments before Game 2 Sunday.

“It don’t matter what you do to Steph and Klay, don’t matter what you with Draymond (Green),” James said. “You give up 45 points off the bench and 25 points off of turnovers on the road, that’s not good ingredients to win.”

The Cavs shot 38 percent, got little from their bench and next to nothing from starting shooting guard J.R. Smith, who took three shots and scored three points in 36 minutes. Yet they showed what they were capable of in the third quarter when they turned a 14-point deficit into a one-point lead. They just couldn’t sustain it.

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An irate Steve Kerr called timeout, smashed and shattered his clipboard, and the Warriors eventually responded with a 15-0 run and outscored Cleveland 40-24 overall. Kerr also broke and threw a clipboard during a game at Madison Square Garden this season. Golden State ended up winning that one too.

“Destruction tends to ease some of the anger,” Kerr said. “I try to take it out on a clipboard instead of a player. So it’s better that way.”

Kerr said the Warriors lost their focus and edge and became too careless with the basketball. But it changed quickly with the subs igniting the charge.

Cleveland led 68-67 after a James’ layup with 2:12 left in the third. Nearly eight minutes and 30 seconds later, Golden State opened up a 96-76 cushion. In that 29-8 run, Curry scored two points and Thompson none. They weren’t even on the floor for much of it. Golden State’s starters totaled eight.

Livingston and last year’s Finals MVP Andre Iguodala did most of the heavy lifting. Livingston scored 10 there. Iguodala had seven of his 12, and played terrific defense all night.

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“This was a strange game for us,” Kerr said. “We’re not used to having both Steph and Klay off like that with their shooting. But if we defend and take care of the ball, we’re always going to have somebody score enough points for us, whether it’s the starters or the bench.”

This was supposed to be a series when James wasn’t supposed to have to score 35 or 40 points a game, especially since he had a healthy Irving and Love unlike last year’s Finals. But everyone needed to do more or less in some cases.

Irving led the Cavaliers with 26 points, but he was 7-for-22 and dribbles too much. That’s his game, but moving the ball is the smarter way to play. He’s allowing the defense to set and relying too much on his one-on-one skills.

James came within an assist of a triple-double — but it became a quiet 23-point, 12-rebound, nine-assist night because of the noise the Warriors’ bench made and all the noise in the arena. He too felt the need to make things happen one-on-one, which isn’t normally his approach.

“They’re a great team when you just hold the ball and pound the ball,” James said. “We got to do a better job of getting the ball moving side to side, getting bodies moving.”

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That’s one of the many adjustments the Cavaliers have to make. If they don’t it could be a quick series. Curry and Thompson aren’t going to be off like that most nights.