BOSTON -- Knicks big men Kristaps Porzingis and Joakim Noah sat out Wednesday night's 117-106 win against the Celtics due to injury, and both will undergo MRIs on Thursday.

Porzingis has missed four straight games with a flare-up of his Achilles injury. Noah sat out with what he described as a sprained ankle.

"I'd say I'm 90 percent ready, still not there yet," Porzingis said before noting the scheduled MRI. "I have to be really careful of how much I do and how explosive the movements are. If not I get a little pinch again in the heel down there where the Achilles start.

"Before [the] Atlanta game [on Monday] I thought I was going to play. But the pregame workout I did some movement, and I felt it again. That made me realize that I'm not ready yet. So it's just really about how much I do explosive stuff. If I take it step-by-step it's fine, and I don't get any pinch or anything. If I try to go to 70 percent to 90, not to 75 or 80, I get a little something. Now I'm being smarter."

Porzingis, who is averaging 19.4 points, 7.4 rebounds and 2.0 blocks this season, said he has not thought about shutting it down long-term.

"Never felt that bad to actually take some time off," he said. "I thought I would be [back] like next game, next game and it has taken long, longer time than we expected. ... [Doctors] want to be smart about it and have me tell them exactly how I feel, not hide it a little bit and say, 'Oh, I'm good.'

"I hate to be out there on the bench with a suit on. You know, I look good out there, but I hate being out there in a suit. I want to be there helping my team, especially in a tough moment like this. We are trying to fix it as quickly as we can and get back on the right track."

Noah, who is averaging 5.6 points and 9.1 rebounds this season, said his ankle began to swell up on the flight to Boston on Tuesday. He is unsure of his status for Thursday night's home game against the Wizards.

"It just happened," Noah said. "It didn't bother me too much in the game [against Atlanta]. The next day after on the plane it just swelled up on me. Frustrating situation.

"I hope it's going to be OK. I mean, it is what it is. I wish I could be there with my teammates right now. We're struggling. I want to be out there, be part of the solution."

The Knicks also were without Lance Thomas, who fractured an orbital bone on Sunday in Toronto.