DALLAS -- New York Knicks forward Carmelo Anthony has been ruled out of Wednesday's game against the Mavericks due to painful back spasms.
Anthony said on Wednesday night that there is no specific timetable for his return.
J.R. Smith started in place of Anthony, who will travel with the Knicks to Oklahoma City following the game, according to coach Derek Fisher.
The Knicks will play the Thunder on Friday.
Anthony told a Knicks official on Wednesday night that his back was "stiff" and "sore" and he was unsure if he would play in Friday's game.
"I just don't know. It's too far ahead for me to even think about right now," Anthony said. "It's gotten a little better, but today was the first day that I actually got to walk around a little bit."
Anthony added that the Knicks' medical staff has not given him a specific timetable for his return.
"They said these things are hard to gauge -- I just don't know how long I'll be out," the veteran forward said.
Fisher said earlier Wednesday that Anthony was "making some progress, but not enough, I think, to be in a game, so it will be day to day."
Anthony left Monday's loss to the Houston Rockets late in the first half with back spasms and did not return.
Anthony said he "couldn't move" once his back locked up. It is the first time Anthony has dealt with spasms.
"I've never felt this way before," he said on Wednesday night. ".... It's gotten a little better, but today was the first day that I actually got to walk around a little bit."
Teammates said Anthony was in severe pain after the game.
"He could barely talk, he said very few words," Smith said. "You could tell the pain he was in."
Anthony visited a doctor in Houston to obtain pain medication that wasn't available in the arena before flying with the Knicks to Dallas. He has not participated in practices or shootarounds, instead opting to receive treatment at the team hotel.
"He's not in a lot of comfort, so [he's] really just trying to rest up and get himself better. We'll be out here tonight and we'll see if we can get a game without him," Fisher said.
This is the second injury for Anthony thus far this season. He revealed last week that he is playing with discomfort in his left knee that first surfaced during the second game of the season
Anthony is leading the Knicks in scoring with 23.2 points per game. Their next-highest scorer is Amar'e Stoudemire (11.7 points per game).
New York fell to 4-11 with Monday's loss and has dropped 10 of its past 12 games.