As coach Leslie Frazier said on Monday, there was no reason to believe receiver Jerome Simpson's leg and back issue was a long-term injury.

Frazier said today that Monday's magnetic resonance imaging (MRI) exam revealed that Simpson's lower left leg weakness and numbness was more the result of a back issue that won't sideline the receiver long, if at all. He will sit out today's practice.

"I don't think it's anything long-term," Frazier said. "We just want him to continue to go through some of the exercises that [head athletic trainer] Eric Sugarman and his staff will take him through today. We may get him back at practice tomorrow and hopefully, for sure, on Friday. But he may be back tomorrow.

So the good news is there's no surgery required or anything like that. He should be fine over time."

The Vikings are counting on Simpson playing on Sunday at Washington.

"All indications are there is a very good chance," Frazier said. "We'll know more as he responds to some of the treatment that they give him today. Hopefully, we'll get him back at practice tomorrow. But we don't think it's anything long-term at all."

Frazier said the best news was Simpson's leg problems had improved since Sunday. Simpson woke up Sunday morning with the leg weakness and numbness and wasn't able to push off on the leg. He was targeted only three times but didn't catch a pass in the team's 30-7 win over the Titans.

"He's much better than he was on Sunday," Frazier said. "He went through the walk-through [today] fine. This is more cautionary just to give him another day of rest and recuperation."

In other injury news:

  • Defensive tackle Kevin Williams has a stomach virus and will miss practice today. He's expected back Thursday.
  • Running back Adrian Peterson's ankle is still a little sore, so he also will sit out today. He's not expected to miss Sunday's game either.

Ponder bouncing back impresses Frazier: Frazier said Christian Ponder's reaction to throwing back-to-back interceptions in Sunday's win was completely different than it would have been during his rookie season last year. Ponder rebounded from the two picks to complete 12 of 13 passes for 100 yards, two touchdowns and no more picks.

"It's a great sign for us because in the past, those two interceptions, I just think back to a year ago where I would have come over and say, `Hey, c'mon Christian, get your head up. Let's go. You got to go back out there,'" Frazier said. "This time, it wasn't necessary. He handled it the way you need the quarterback of your team and one of the leaders of your team to handle it. He went over to the bench, looked at the pictures, talked to the coaches and went right back out. He had no ill effects from it. That's a great sign for our players because they look to him and his body language and his approach afterwards. It was so good for us going forward."

RGIII introduces new look to Vikings' defense: The Vikings are banking on rookie quarterback Robert Griffin III playing on Sunday. RGIII was knocked out of last week's loss to the Falcons with a concussion, but he's been cleared to practice today.

"It's a different dynamic," Frazier said. "They present an option [attack]. We haven't had to prepare for option football at all this season. We're watching tape Monday and Tuesday of a quarterback who not only presents a threat throwing the football, but getting on the perimeter of your defense and being able to pitch it or keep it and make plays. I think he has over 200 yards rushing (241) already and over 30 attempts (42). So it creates some other issues that we haven't faced this season. It forces you as a defense to be very disciplined about what you're doing and you have to tackle well.

"He's a multi-threat quarterback that creates a lot of problems for defenses because they do some things you don't ordinarily see at our level."