The Knicks drafted Porzingis fourth overall in June and have been pleased with his progress in the preseason.
The 7-3 forward averaged 7.5 points on 37 percent shooting in four preseason games. He knocked down 37.5 percent of his 3-point attempts and grabbed 6.0 rebounds per game.
Knicks coach Derek Fisher discussed the thought process behind starting Porzingis after the team shootaround on Wednesday morning.
"I just think his versatility changes what can happen on the floor because of the multiple skills offensively and defensively," Fisher said. "We obviously drafted him No. 4. Why should we hold him on the shelf? It doesn't mean he's going to start all season, but we feel like we've seen enough that he deserves the opportunity to show what he can do."
Vujacic will start in place of injured shooting guard Arron Afflalo for New York.