Jalen Brunson twisted his ankle on Friday but was able to practice Sunday, avoiding major injury.
Starting center Mitch Robinson was not as lucky - he injured his ankle Friday also.
Robinson did not practice Sunday and was sent for further tests on the ankle.
Coach Thibodeau did not provide specifics on the injury or testing.
Thibodeau said he doesn't know if Robinson will be out long-term.
Robinson initially hurt the ankle against the Celtics on Friday. He got X-rays that were negative.
Robinson is one of the NBA's best rebounders and rim protectors, so missing games would impact the Knicks.
If Robinson is out, Isaiah Hartenstein would likely replace him as starting center. Thibodeau said center depth is a strength for the team.
By Jessica S. Norris