OAKLAND, Calif. — Warriors coach Steve Kerr and the Cavaliers’ J.R. Smith agree on one thing: This NBA Finals series ain’t over, despite the staggering blow of Cleveland losing starting point guard Kyrie Irving to a broken left kneecap.

With Matthew Dellavedova, the undrafted St. Mary’s product via Australia, as the Cavs’ starting point guard facing MVP Stephen Curry and already down 1-0, it’s hard to fathom Cleveland having a chance. Game 2 is on tap for 8 p.m. Sunday at raucous Oracle Arena.

“We just look at it as we’re supposed to win,’’ Smith, the former Knick, said Saturday. “People can call us the underdogs all they want, but we look at it as we’re supposed to win. I really don’t care [about dire predictions]. People have been counting me out my whole career and I’m in the NBA Finals.’’

LeBron James called it “a bitter pill to swallow,” but not the death blow.

“I understand we were the underdog coming into the series and with Kyrie being out, people are writing us off,’’ James said. “That’s fine. I’m motivated to get our guys ready to go, and we will be ready. I said it’s going to be the most challenging season of my career from the beginning and this just adds onto it. We’re undermanned right now, but we’ve got guys in the locker room ready for the challenge and look forward to it.”

While Irving underwent surgery Saturday in Cleveland, Kerr admitted his job is to convince his team the Cavs are worthy despite not having Irving or Kevin Love, and relying heavily on Smith, Dellavedova and Iman Shumpert. Smith and Shumpert were scoreless after halftime in Game 1’s overtime loss.

“If we have a letdown in The Finals, there is something fundamentally flawed with us each individually,’’ said Kerr. “There is no way that can possibly happen. We’re lucky to be up 1-0. This is a team that got to The Finals beating the No. 1 seed in the East without Kyrie for a couple of games. The challenge is still enormous. It’s reminding our guys they’re still a great team. They’re still loaded with talent.’’

Cavs coach David Blatt said the team “requests no sympathy.’’ The Israeli legend said Irving’s knee injury stemmed from knee-to-knee “contact’’ — unrelated to prior tendinitis.

Out three-to-four months, Irving could miss the start of training camp.

“Your heart goes out to him,’’ Curry said.

Curry had a solid if not spectacular Game 1, scoring 26 points with eight assists after a jittery start. He nailed four straight free throws to start an overtime in which the Warriors shut out Cleveland until the final, meaningless seconds.

Now Dellavedova, a slow-footed defender, has to guard Curry. In one sensational moment in the late stages of regulation, Curry executed a series of jukes and feints, freezing James and burying a 3-pointer. He has hit 12 straight 3-point shots from the left corner, of which he was reminded.

“You jinxed me already,’’ Curry said. “I’m not the fastest guy, not the most athletic or explosive, so I need to be able to have change of speed or direction control the ball to create space and get into a jumper or get into the lane.”

Metrics show James on the court minus Love and Irving has been successful. The two wins over the Hawks without Irving were encouraging to the Cavs. Cleveland also played well against the Bulls when Irving played limited minutes, particularly in the series-clinching Game 6 in Chicago, when Dellavedova erupted for 19 points.

James took a career-playoff-high 36 shots in Game 1, and Curry predicted less of an isolation offense.

“LeBron’s going to look to move the ball more and get everybody some better looks,’’ Curry said.

“Dellavedova has a different game than Kyrie, so when he’s involved in pick-and-rolls, you have to know his strengths, stay tight on him because obviously he’s a knockdown shooter. So if you get him easy looks worrying about LeBron sending extra help when you really don’t need to, he can kill you.”

Shumpert is not worried about the naysayers.

“We’ve had to play other games without Kyrie, and I’m sure we had some doubters,’’ Shumpert said. “That’s why they’re not in the locker room.’’