Head coach Jeff Hornacek later told reporters he believes the issue is minor and Porzingis should practice tomorrow.
Porzingis, 22, finished second on the Knicks in scoring in 2016-17 behind Carmelo Anthony, second in rebounding behind Joakim Noah and first in blocks per contest. Following up his excellent rookie season, he reinforced the belief that he is the team's most important building block going forward.
But injuries and durability have become a concern for Porzingis, who battled Achilles tendinitis throughout last season. As Kevin O'Connor of The Ringer noted, Porzingis has dealt with an "injured left Achilles, groin, thigh, quad, hip, right ankle and foot" since 2015.
Porzingis told reporters in April the Achilles tendinitis stole his rhythm:
"Until I got hurt with the Achilles, I was playing a very high level, very consistently, every night, but still we weren't playing at the level that we wanted to as a team, so that didn't really do anything for me. But I liked the consistency. I was out there playing at a high level. Then the injuries, little things [that] happened got me out of my rhythm. Then it was kind of on and off, some games good, some games not so good. I was trying to find that rhythm for a long time. Then the second part of the season, it was just a big fight for us and mentally tough. I think I grew from this season."
The Knicks are banking on that continued growth. With Derrick Rose's departure in free agency and Anthony now traded, Porzingis is the team's centerpiece.