Peterson will have surgery in the next 7-10 days and should recover in the next 8-9 months, Sugarman told reporters Monday.
Sugarman said Peterson suffered torn medial collateral and anterior cruciate ligaments and that the medial and lateral meniscus were also damaged.
"Adrian is, I feel, very unique," said Sugerman. "If there was anyone that is going to be able to recover from this injury, it's Adrian Peterson, and you may ask why, and it's because Adrian has a great work ethic. Adrian has the DNA to heal quickly, which he has shown in the past.
Answering the question of when Peterson will be ready to play, Sugerman said the goal is to have him "ready for the beginning portion of next season."
"He is extremely optimistic, positive, even in the midst of rehab ahead of him, he is extremely positive about being able to come back and be as good or better than he was before and that's the Adrian we're all accustomed to seeing," Frazier said Monday. "He sets his goals extremely high and he's one of those guys who, when he puts his mind to it, there's no reason to ever doubt that he can't achieve what he really puts his mind to."
Peterson was placed on injured reserve Monday. Rookie running back Caleb King was promoted from the practice squad to take his roster spot.
Sugerman added that quarterback Christian Ponder, who suffered a concussion against the Redskins, is "doing great" and doesn't have any remaining concussion-like symptoms. The hope is Ponder will be able to exercise without symptoms so he can be cleared by a physician and then an outside neurologist to return to practice.
Frazier said left guard Steve Hutchinson (concussion) and cornerback Asher Allen (concussion) have yet to be cleared to practice.