Vikings running back Adrian Peterson tore both the anterior cruciate ligament and medial collateral ligament in his left knee Saturday, but the team is optimistic he will be back early next season.

Minnesota's head trainer said Monday that Peterson's "very serious" injury also included some damage to the medial and lateral menisci in his knee.

Peterson was injured on a helmet-to-knee hit from Redskins safety DeJon Gomes on the first play from scrimmage in the third quarter. He will probably have surgery in the next 7-10 days, trainer Eric Sugarman said, although no surgeon has been selected yet.

"We do think the potential is to have him ready for the beginning portion of next season," Sugarman said.

Vikings head coach Leslie Frazier said Peterson, who was playing in just his second game since missing three with a high ankle sprain, was "optimistic and positive even in the midst of the rehab ahead of him."

"That's the Adrian we're all accustomed to seeing," said Frazier. "He sets his goals really high."

The timetable for Peterson's return was fluid. Sugarman said they expect "most people" to recover from the injury in 8-9 months, placing the target for Peterson's return near the beginning of next season.

Sugarman said Peterson's conditioning and genetics give him a unique ability to get better "quickly and safely" from the injury.

"If there's anyone that's going to be able to recover from this injury, it's Adrian," the trainer said.

Sugarman said Vikings quarterback Christian Ponder was "doing excellent" and "really doesn't have any symptoms" after suffering a concussion one play after Peterson was hurt.

Ponder was taken out of the game because he had symptoms of a concussion and will go through all the normal tests this week, Sugarman said.

Peterson finished the season with 970 rushing yards and 12 touchdowns on 208 carries. It was the first time in his career that he didn't eclipse 1,000 yards rushing.

Toby Gerhart will be the Vikings' starting running back for the final game of the season Sunday against Chicago.