The Knicks will have to chase the NBA Cup without one of the most important pieces in their rotation.

Backup guard Miles McBride, who missed Tuesday’s quarterfinal win over the Toronto Raptors, will be sidelined for at least a week with a sprained left ankle, the team announced on Thursday. He will be re-evaluated in seven days, ruling him out of Saturday’s semifinal against the Orlando Magic and should New York advance, Tuesday’s NBA Cup Final in Las Vegas against the winner of the San Antonio Spurs–Oklahoma City Thunder quarterfinal out West.

“Obviously we miss him, we want him back,” team captain Jalen Brunson said after Thursday’s practice. “Gotta pick up a lot of slack on both sides of the ball without him being out there.”

McBride turned his ankle late in Sunday’s 106-100 win over the Magic on a drive to the rim. X-rays were negative, but he later left the Knicks’ training facility in a walking boot before undergoing the MRI that confirmed the sprain.

“He’s able to do so much for us, and so definitely we need to fill that gap,” Brunson said. “We’re just gonna have to do what we’ve gotta do until he’s back.”

The timing is brutal for both player and team. McBride is in the middle of a breakout season under new head coach Mike Brown, posting career-best marks in scoring (11.2 points per game) and three-point accuracy (44.2%). Among players attempting at least six threes per game, only Cleveland’s Sam Merrill, Denver’s Jamal Murray, and Milwaukee’s league-leader A.J. Green have been more efficient.

And the shooting doesn’t even account for where he might be missed most: defending the point of attack. The Knicks’ quarterfinal win over Toronto was their first in the four games McBride has missed this season — a reflection of how much impact he brings to the perimeter.

Brown acknowledged his young guard’s importance before the team took off for Las Vegas on Thursday

“I think it’s a collective deal,” he said. “Not one person is gonna replace any other one person.”

Without McBride, New York now leans harder on its reserve guards. Jordan Clarkson has been the most consistent source of bench offense, giving the Knicks a scoring jolt sorely lacking from last season’s bottom-ranked second unit.

“He’s definitely one of the best sixth men ever in our game. He’s won the award, and the things he’s been able to do in that role have been great,” Brunson said of his teammate. “So I expect him just to come and be aggressive and be who he is. We have that confidence in him, and he has that confidence, so I don’t see a drop-off. I just see the next-man up mentality.”

Clarkson is averaging 9.9 points in 20 minutes per game — and more importantly, he’s doing it in a way Brown says is coming within the flow of the offense.

“Jordan’s had a fantastic year for us. He’s given us a huge spark coming off the bench, and what I like about the way he’s scoring the basketball is he’s not getting himself in trouble by playing off of one foot when he gets in the paint,” the coach explained. “He’s real patient and methodical with what he does until he can get to his spot, and then when he gets to his spot, he’s usually playing off of two feet — which allows him to still spray the basketball if a lot of help comes.

“So I like that offensively, and then defensively, he’s trying to play with a level of physicality that we like to play with as a group, whether it’s on the ball or off the ball, and when you’re a small guard, you have to be physical in order to survive in our league. And he’s trying to do it.”

Brown threw second-year guard Tyler Kolek into the fire, too. It’s all hands on deck in orange and blue with McBride out of the rotation, and Kolek logged eight meaningful minutes in Tuesday’s win over Toronto.