OKLAHOMA CITY — Center Willy Hernangomez, the young building block who was a first-team All-Rookie selection, found himself out of the rotation in the season opener Thursday versus the Thunder. As expected Enes Kanter started and Kyle O’Quinn got 22 minutes as the backup.

With 3:46 left, Hernangomez was put in during garbage time of the Knicks’ 105-84 season-opening loss. The Spaniard found out at the morning shootaround from coach Jeff Hornacek he wouldn’t be in the rotation and it’s about his lax defense.

“He told me be ready,” Hernangomez said. “I’m not worried about that. It’s the first game. I’m just mad we lost.”

“He knows I can score. I have to focus on defense, try to do defensive things. Coach wants me to put my mind on defense. I have to keep working on defense and hopefully the minutes will come.’’

Hornacek said Hernangomez is “not far behind.’’

“We have a lot of bigs,’’ Hornacek said. “KO and Enes earned the minutes in training camp.’’

Kristaps Porzingis has lofty individual goals that go beyond making his first All-Star Game, which he made known over the summer.

In an interview with the Players Tribune, Porzingis listed two other honors in his sights — one likely unreachable, considering his defensive rebounding numbers.

“As far as individual goals … I want to make the All-Star Game, I want to be Defensive Player of the Year, and I also feel like I could be the Most Improved Player of the Year,” Porzingis said. “If I do those three things, then that’s going to help the team win a lot.”

Porzingis now is the No. 1 option with Carmelo Anthony gone, but winning most improved might be tough considering he posted nice numbers last season, averaging 18.1 points per game on 45 percent shooting. The Knicks coaching staff has tried to make Porzingis a better defender by getting him to foul less and not leave his feet on fakes.

Porzingis, who had 31 points and 12 rebounds against the Thunder, obviously feels his defense will be on the rise. He blocked three shots in the preseason game against the Nets while playing just the first half and blocked a shot against Oklahoma City on Thursday.

“We worked on our defense 90 percent of practice,” Porzingis said of training camp. “The drills were disgusting. Your legs were burning.”

The 7-foot-3 Latvian had a big boast last preseason, saying one day he’d like to post a quadruple-double. Porzingis, 22, played in just two preseason games because of a hip injury.

Center Enes Kanter, obtained in the Anthony deal, and Thunder center Steven Adams had been going at it on text as tipoff loomed.

“Actually, he told me that on the jump ball, I’m going to elbow you,” Kanter said. “He told me after I got traded, ‘Watch out. I’m gonna elbow you from the jump ball.’ But I texted him a couple of days ago to say it doesn’t matter you’re on different team, you’re always my brother. Not just him. Russ [Westbrook], other guys, I can’t say enough how much they helped me off the court.”

Asked if he thought Westbrook would say hello, Kanter answered: “He’s mental. Probably not. But I’m going to say hi to him.”

Doug McDermott on his Oklahoma City return: “Fans here are great. I was only here for a few months. It felt like and they’re still acting like I was here for a few years.’’

Suspended Joakim Noah is traveling with club because Hornacek still is adding new plays.

As projected, Hornacek finally made it official Thursday with a starting lineup with Ramon Sessions and Tim Hardaway Jr. in the backcourt and Courtney Lee, Porzingis and Kanter up front.