For those watching the ABC broadcast, I think Bill Simmons summed it up nicely with his head buried in his hands.
Update: He's headed to the hospital to get an MRI.
Update: And the hits keep on coming, Mark Murphy is reporting that the Celts fear an ACL tear.
Celtics source says Rondo may have torn ACL - getting MRI for it now at New England Baptist.— Mark Murphy (@Murf56) January 27, 2013
We'll have more on this story as it develops. Needless to say, if Rondo is done, so is our season.