"All indications are there's a very good chance (he'll play)," Frazier said. "We'll know more, how he responds to some of the treatment they give him today."
Simpson started last week's game against the Tennessee Titans, but only played in 35 percent of the team's offensive snaps. The Vikings had nine players catch passes, but Simpson wasn't one of them.
"We don't think it's anything long-term," Frazier said. "We just want him to continue to go through some of the exercises (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."
Frazier said no surgery will be required.
"Everything they told me, it's just something attributed to something going on in his back, so they're taking him through some different exercises," Frazier said. "But he's improved, that's the good news. He's much better than he was on Sunday. He went through the walk-through fine (Wednesday morning). This is more cautionary to give him another day."
Although Simpson didn't know the extent of the injury or what was causing it, he was concerned after Sunday's game.
"Just being injured, my level of concern is always high," he said. "I'm pretty sure I'll get through this and just keep the faith and just do what the doctors say."
Simpson said the leg loosened up some during the game, but he "didn't have that elusiveness about me."
After signing a one-year, $2 million contract with the Vikings in the offseason, Simpson was suspended for the first three games of the season for violating the league's substance abuse policy. He pleaded guilty March 1 to the felony charge resulting from about 2 pounds of marijuana shipped to his northern Kentucky home in September.
Simpson was a second-round draft pick from Coastal Carolina in 2008. He caught 53 passes for 758 yards and four touchdowns for the Cincinnati Bengals last season.
RG III ON THE MEND
Redskins QB Robert Griffin III is practicing Wednesday and will be evaluated every day after practice following what was termed a "mild" concussion in Sunday's game.
"He'll practice. Every day is an evaluation period," Redskins coach Mike Shanahan said. "After practice, he'll go through the test."
Shanahan said the team wouldn't know until Friday whether or not RG III would play, but it's looking very likely at this point.
Of course, that would be a big help to a Redskins team looking to break an eight-game losing streak at home. Griffin has completed 69.1 percent of his passes for 1,161 yards, four touchdowns and one interception for a 101 passer rating. He also has 241 yards rushing on 42 carries and another four touchdowns.
"Defenses will play a little more aggressive to him when it comes to him running the ball. I also see a lot of different looks that I didn't see in the last few years," Washington receiver Santana Moss said of RG III's impact on opposing defenses. "Teams used to play us deep and now you see a couple safeties in the box here and there."
THE FORMER VIKINGS
Former Vikings defensive backs Cedric Griffin and Madieu Williams are now with the Redskins.
Griffin hasn't started a game, but he played in the first two contests, registering a combined 11 tackles and three passes defensed. He has missed the last two games with a hamstring injury
Williams has started all five games at free safety, garnering a combined 30 tackles and four passes defensed.
Tim Yotter is the publisher of Viking Update. Follow Viking Update on Twitter and discuss this topic on our message boards. To become a subscriber to the Viking Update web site or magazine, click here.