The Knicks could be without one of their top perimeter defenders for Game 4 of their first-round playoff series against the Cavaliers.

Quentin Grimes suffered a right shoulder contusion late in the second quarter of the Knicks’ Game 3 rout of Cleveland and is listed as questionable for Game 4 on Sunday.

Coach Tom Thibodeau said Grimes’ status would be known on Sunday. It was uncertain how the second-year guard suffered the injury.

“There’s a lot of contacts going through screens, so it could have happened on any one of those,” said Thibodeau, who noted that Grimes was “feeling a little better” on Saturday.

Josh Hart started the second half in place of Grimes, who left the game with 2:13 left in the second quarter and didn’t return.

He was seen on the bench in pain.

Though Grimes hasn’t done much on the offensive end, going 2-for-11 from the field in the first three games, he is a starter and a valuable defender.

Hart likely would start in Grimes’ place if he isn’t available, with Miles McBride filling Hart’s role on the second unit.

“Obviously he provides spacing for them, a defensive mindset,” Cavaliers coach J.B. Bickerstaff said. “But if they go the same way with Josh Hart, Josh Hart has proven to be extremely impactful, and impacts winning in a huge way. So we’ll prepare and be ready for them.”

Following the Game 3 win, Knicks fans celebrated the victory in the streets outside of the Garden, with multiple videos going viral.

Jalen Brunson noticed them.

Included were one showing a fan climbing a street sign and a few others with fans playing a makeshift game of pickup on Eighth Avenue with a basketball hoop affixed to the top of a school bus.

“It’s impossible not to see that,” Brunson said. “New York fans are great. When they’re excited, it’s amazing to see. It’s the best fan base I’ve ever seen.”

The Knicks ruled out reserve center Jericho Sims (sore right shoulder) for Game 4.