Porzingis worked out prior to the game to test the injury and met with the team's medical staff before tipoff, when it was determined that he wouldn't play.
"I think he just wasn't feeling exactly right on some of his moves," Knicks coach Jeff Hornacek said. "So after talking with the doctors, we just felt that we'll keep him out ... They'll continue to work on it. He felt better, he seemed like he was almost ready to go today. So hopefully he progresses in the next day-and-a-half."
Despite Porzingis' absence, the Knicks spoiled Anthony's first game back at Madison Square Garden since being traded in September with a 111-96 win over the Thunder.
Porzingis originally suffered the injury in the first half of Thursday's win over the Brooklyn Nets. The 22-year-old twisted his left knee when he received the ball in the post.
"I felt my knee buckle a little bit, and I felt a little pain there. So it's more about being cautious," Porzingis said Thursday night. "I had a little shock pain there, and that's it."
The third-year forward played through some discomfort later in the half, but said he felt instability in the knee in the third quarter, so he removed himself from the game.
The Knicks appear to be taking a cautious approach with the injury, which is not expected to sideline Porzingis for an extended period.
He's officially listed as day-to-day and was labeled as questionable entering Saturday's game. The Knicks play next in Charlotte on Monday. Hornacek expressed some doubt that Porzingis would be healthy enough to suit up against the Hornets.
"The little things that were getting him when he was making certain moves, I don't know if that just disappears overnight," Hornacek said. "So we'll have to see."
The Knicks (16-13) are 2-4 in games that Porzingis misses due to injury (that record includes their win over the Miami Heat on Nov. 29, in which Porzingis exited three minutes into the first quarter with an ankle injury).
The third-year forward leaves a significant void for New York when he's hurt. Porzingis is averaging 25.5 points, 6.6 rebounds and 2.1 blocks per game.