EDEN PRAIRIE, Minn. (AP) -- Most days, Adrian Peterson went through rehab drills looking as if he were never injured.

No one could've foreseen the rapid recovery Peterson has made since that bionic left knee of his was severely damaged near the end of a lost 2011 season for Minnesota. No one could have predicted these weekly gallops down the field and through the NFL record book.

With two games to go, Peterson needs 294 yards to break Eric Dickerson's all-time single-season rushing record. He is 188 yards from becoming the seventh player in league history to reach 2,000 yards in one year.

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Dec. 24, 2011:

The Vikings were playing at Washington the day before Christmas, a meaningless matchup between teams well out of postseason contention. The end of a routine 3-yard run early in the third quarter by Peterson, the throwback thoroughbred the Vikings have hitched their franchise to in a league now dominated by the forward pass, ended with excruciating pain.

Redskins safety DeJon Gomes dived at his lower left leg to take him down, tearing Peterson's anterior cruciate and medial collateral ligaments in the process. Peterson, lying face down on the grass, knew immediately "something bad" had happened. By the time head athletic trainer Eric Sugarman and team physician Dr. Joel Boyd raced over from the sideline, Peterson was screaming, "Why me? Why me?"

Sugarman and Boyd performed the Lachman test, where the leg is pushed and wiggled to gauge the stability of the ACL.

"It was just gone," Sugarman said. "So now your worst nightmare is confirmed."

By the time the game was over, Peterson's attitude had already turned. His knee in a brace, sitting in the training room, he asked Sugarman, "Hey, what do we do next? Where do we start? How do we get better?"

"His grieving was very short-lived," Sugarman said.

The rehabilitation of one of the best running backs in NFL history began.

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The winter:

The first three months of the reconstructive knee surgery recovery are always the hardest, and even for Peterson this was no different. The mornings were dark and cold. Most of his teammates were gone. There were occasional text messages Sugarman had to send to encourage Peterson not to let up. The swelling had to subside first, before he could start the process of restoring his range of motion. The pain from both the incision and the bone that had to be broken to allow the ligament to be replaced was intense. But as soon as Dr. James Andrews performed the procedure in Birmingham, Ala., on Dec. 30, Peterson was ready.

"I had in my mind from the moment I got out of surgery that I was going to be back, that I was going to be good and healthy," Peterson said.

In three weeks, he was walking. After six weeks, he began to jog in the pool. At eight weeks, he was sprinting, with the jets turned on for resistance. Then, 10 weeks after the operation, he ran on hard ground for the first time. Peterson and Sugarman were the only people on the indoor field at Winter Park that day.

"The first time I have a guy run after an ACL, they look like they have marbles in their shoe," Sugarman said. "He probably had done it on his own without telling me before that, I would guess. But the guy took off and ran across the field like, `Whoa! He looks totally normal.' This isn't supposed to happen. So that was awesome."

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The spring and summer:

On the first day of the team's conditioning program in late April, the players lined up for sprints. Peterson was working with Sugarman on the side when he saw what was going on. Granted permission to participate, Peterson jumped in line with the rest of the runners. His exhausted teammates wore expressions of disbelief.

"He finished in first four different times," head coach Leslie Frazier said.

Peterson also spent time at his offseason home in Houston, where he worked with physical therapist Russ Paine at the Memorial Herrmann Sports Medicine Institute. Paine picked up where Sugarman and his staff left off.

When Peterson showed up for his sessions at the clinic, the other athletes rehabbing there stared in amazement as he sprinted at the top speed levels of the treadmill. When he lined himself up at the leg press machine, he asked that the prescribed weight be doubled.

"I really wasn't playing around. I was on a mission," he said.