Vikings coach Leslie Frazier said Pro Bowl running back Adrian Peterson will have his right ankle examined Monday to determine the extent of his injury.

Peterson injured his ankle in the second quarter when Washington's Lorenzo Alexander fell on it while making a tackle. Peterson tested his ankle on the sideline but he was not able to return. He is expected to have an MRI on Monday.

"Obviously I got my ankle rolled up so I'll check in with my training staff [Monday]," Peterson said. "It started to throb a little bit. As you saw, I was trying to keep it loose jogging and trying to plant on it."

Rookie Toby Gerhart replaced Peterson and carried the ball 22 times for 76 yards and his first NFL touchdown.

"He had to step in there and play a full role," Peterson said. "I thought he did a great job. He really helped us keep some drives alive."

Peterson had a great start with 36 yards rushing and a 34-yard catch. He said he felt like he was in store for a big day if not for the injury.

"I felt real good," he said. "But it wasn't meant to happen."

Also, defensive end Ray Edwards said he will get an MRI on his right ankle Monday. Edwards suffered his injury late in the first half and did not return.