Vikings defensive end Everson Griffen did not practice Thursday and might not play on Sunday at Washington as he mourns the unexpected death of his mother. Sabrina Scott had been visiting her son in the Twin Cities when she died Wednesday.

"It's purely up to him when he comes back," Vikings coach Leslie Frazier said. "There is no timetable."

Griffen was at Winter Park when Eden Prairie police called Frazier with the news. Frazier called Griffen into his office, where the officers broke the news to Griffen.

"As you can imagine, it was tough news," Frazier said. "There was nothing that could have prepared him for that news. Completely unexpected. It's hard. He loved his mom, like we all do. And to have no clue that something like this was on the horizon was tough."

Frazier and several players spent part of Wednesday evening at Griffen's home. Frazier said he had no details of the cause of death.

Griffen, a backup, is tied with Jared Allen for the team lead in sacks with three. If he doesn't play, it could mean increased reps for second-year defensive end D'Aundre Reed.

Peterson practicesAfter missing Wednesday's practice because of an ankle sprain, running back Adrian Peterson returned on a limited basis Thursday.

Peterson said there's no doubt he'll be playing.

"I wouldn't say [my ankle] is a concern, but I definitely want to get back to feeling good," Peterson said. "But I don't think it's going to hinder me being able to play and push through.

"I've pushed through worse ankle injuries than the one I have."

Receiver Percy Harvin was added to the injury report when a hamstring tightened up on him during Thursday's practice. Frazier decided to lighten Harvin's load as a precautionary measure.

Simpson uncertainAlthough receiver Jerome Simpson (foot/lower back) returned to practice on Thursday, he was limited.

"Jerome was a little bit better," Frazier said. "We'll have to see how he is [Friday] and see if he can put together some back-to-back days. I want to see how he does [Friday] and talk with him after practice."

Other players who were limited in practice Thursday were: left guard Charlie Johnson (lower back), linebacker Marvin Mitchell (calf), safety Andrew Sendejo (ankle) and cornerback Antoine Winfield (knee).

Quarterback Christian Ponder (knee) was on the injury report, but had full participation in practice.

Safety Mistral Raymond (ankle) didn't practice and will miss his third consecutive game on Sunday.

Asked what kind of progress he's made since dislocating his right ankle during the Sept. 23 win over the 49ers, Raymond said, "I'm able to walk, for one. That's a huge step."

Raymond started walking without a cast or boot a week ago.

RG3 'a nightmare'The Redskins have gotten creative with their playbook. To complement quarterback Robert Griffin III's multi-dimensional talents, the team is mixing in doses of option offense that Vikings defensive coordinator Alan Williams concedes are "a nightmare for any coordinator."

Asked when was the last time he had to prepare a team to face the option, Williams, an assistant at William and Mary from 1996 to 2000, said, "Probably the Delaware Wing-T, coach Tubby Raymond in the college days. And it drove me crazy. So I'm glad the NFL isn't filled with those kinds of offenses."

Griffin is completing an NFL-best 69.1 percent of his passes and has run 42 times for 241 yards and four touchdowns.

Coming off a concussion Sunday, Griffin was limited in practice Thursday, but Washington coach Mike Shanahan said the rookie looked "good."

Etc.• The Vikings waived guard Tyler Holmes from the practice squad and replaced him with defensive end Ernest Owusu. It's not the first time they have flip-flopped this season.