Peterson, the NFL's leading rusher, left in the second quarter after being tackled on an icy field.
"I really don't know too much about it. I'll find out more (Monday) after I get my MRI done, but yeah, mid-foot sprain," said Peterson, who was limping but without crutches after Minnesota's 29-26 loss.
"We did X-rays, and it came back pretty clear," he said.
At the time of the injury, Peterson recalled thinking, "I hope I didn't break anything; that's what it felt like."
Peterson caught a short pass from Matt Cassel and headed to the right sideline. He was tackled by Arthur Brown near the Minnesota bench and immediately threw away the ball as he headed down toward the slick turf.
"I haven't seen the replay, but my foot was extended and kind of got rolled up, kind of like a horse-collar tackle type," Peterson said. "I just felt it pop a couple times and the pain was excruciating. I came in and tried to tape it up again after getting the X-ray done. I just couldn't do it with the push off."
Peterson, the 2012 NFL MVP, began the day as the NFL rushing leader with 1,208 yards.
He expects to add to that total in the weeks ahead. Asked if this could be a season-ending injury, he said, "Not at all. You should have seen me in here trying to get back out there. I kept my pads on, too, until the third quarter, until I finally was just like, 'I'm not ready to go.'"
Peterson missed four games in the 2011 season with a torn knee ligament.
"Not my knee at all. It was all my ankle and foot area," he said of this injury.
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