WASHINGTON — Kevin Seraphin’s first chance to show something to his former Wizards coach, Randy Wittman, was put on hold. Seraphin missed the Knicks’ 115-104 win over the Wizards at Verizon Center with a swollen right knee — the same knee he had scoped two years ago.

Seraphin was none too pleased coach Derek Fisher decided to be cautious and sit him because of how much he looked forward to facing Wittman’s team.

“I’ve been waiting for this since I signed,’’ Seraphin said in the visitor’s locker room at Verizon Center, “I talked to Fisher and told him I kind of mad. He told me it’s preseason. If I play tonight you’ll be out tomorrow. He was like: ‘Take your time. We’ll see them in a couple of weeks [Oct. 31].’ ”

Seraphin also seemed to get a rise over Wittman’s comment Friday night about his Washington playing time. Seraphin told The Post during training camp he needed a change because of inconsistent minutes in five seasons with the Wizards.

“Listen, the players dictate who plays and what minutes they get,’’ Wittman said. “I’m not going to get into inconsistent minutes or not. He played. I wish him luck.’’

Seraphin’s eyes got bit large when told of Wittman’s remark and paused for several seconds. “He said players dictate playing time?’’ Seraphin asked. “I don’t really agree there. What can I say. I was doing pretty much everything right, working hard.

“I’m not mad at all. That’s the business. He has the right to play me at the end of the day. … I don’t think he didn’t want to play me.’’

It appears the Knicks are being cautious with Seraphin because he has a history with his right knee. Wizards insiders say they believe Seraphin once had knee swelling because of his weight. But he lost 20 pounds entering last season, to about 270. The Knicks are listing Seraphin at 278 pounds, and he doesn’t look like he has just come off a gluten-free diet.

“It’s not something big — something small,’’ said Seraphin, who had a strong preseason opener with 14 points on 7 of 11 shooting. “I had a good training camp. It’s just like swollen. Nothing crazy like I’ll be out for a few weeks.’’

Fisher, who pushed for the Seraphin signing at the $2.8 million room exception, said: “The sky is kind of the limit for Kevin how he grows and evolves as a player.’’

Fisher also said Seraphin’s offense is of no concern, but he still can become “a better defender and rebounder.’’

Arron Afflalo missed his second straight game with a sore hamstring. … The Knicks again used the starting lineup of Jose Calderon, Sasha Vujacic, Carmelo Anthony, Kristaps Porzingis, and Robin Lopez.