Nerlens Noel tore his ACL on Tuesday, which was discovered with an MRI on Wednesday.
"I'd be surprised if he comes back," his brother Rodman Noel said on Wednesday. "Right now people still say he'll be a top-five pick. It would only be smart to take it while you can."
Noel's rehab is expected to take six to eight months.
"What devastated him more than anything else was not being able to finish out the season," Rodman said. "Especially being his first year of college. He really wanted to play in the NCAA tournament."