With Rashard Mendenhall ailing, rookie Andre Ellington (left) is in line to start at running back Sunday against Atlanta, while Ryan Williams (right) is just hoping to be active for the first time this season.

Rashard Mendenhall is doubtful to play Sunday, the toe that has been bothering him off and on for weeks now bad enough to likely sideline the veteran running back against Atlanta.

That means rookie sixth-round draft pick Andre Ellington, who has averaged 6.4 yards a carry backing up Mendenhall, will probably get his first start against the Falcons.

"I was already getting the majority of the plays on offense, but my role is just a little bit bigger," Ellington said.

Much less certain is whether former second-round pick Ryan Williams, the only member of the 53-man roster to have not been active for at least one game so far this season, will finally get that chance should Mendenhall be out.

Coach Bruce Arians said Friday that even if Mendenhall sits, Williams' status will be determined based on the other injuries and inactives for the

game. Arians said without Mendenhall, Ellington's backup would be fellow rookie Stepfan Taylor. Alfonso Smith would remain the third-down back because of his pass-protection skills.

With no absolutes, Williams – clearly disappointed he has not yet played – wasn't sure how he should approach the news Mendenhall likely will be out.

"I have no answers for anything," Williams said. "I don't know. I don't know what is going to happen this Sunday. We'll see what happens on Sunday.

"I just approach every day like I have been doing. Continue to work hard in practice and whenever they tell me I get to go as a definite I will go. But I haven't heard anything of that sort. I just control what I can control."

A reason Arians said Williams has not been active is his lack of playing special teams, but Williams said he thinks he could play special teams if asked.

"I believe a lot of guys can play special teams as long as you put forth the effort and get the scheme down right," Williams said. "But if that's what is keeping me off the field, then I guess that's what is keeping me off the field."

"I think the only person that really knows is B.A.," Williams added. "I feel when the time is right for me to get out there he will tell me to get out there. Until then I'll keep playing my role."

That role will be behind Ellington and Taylor for now. Arians said he was "very confident" in Taylor's abilities.

But Ellington will be in the spotlight first. Mendenhall has 92 attempts this season for 291 yards,

a disappointing 3.1-yard average. The toe has been a problem, Arians said, so taking a game off before the bye week should give Mendenhall time to recover.

Ellington has been more effective thus far, though. On 28 rushing attempts, Ellington has averaged 6.4 yards a carry. Ellington also has 20 receptions, sometimes splitting out wide as a receiver, and everybody – from Arians to offensive coordinator Harold Goodwin to general manager Steve Keim – has said repeatedly they do not want to play the slightly-built Ellington so much that he wears down. That wouldn't change even if Mendenhall is out, Arians said.

"I look at him the same way," Arians said. "It's still a situational … I don't use the word 'committee' but we'll monitor how many times he carries."

Ellington is expected to be featured more Sunday if Mendenhall is out, however. Ellington doesn't think twice about the possibility the coaches might be watching his workload, but he has also never shied away from saying he thinks he couldn't handle more.   

"I don't have a set number," Ellington said. "I just play ball. You start thinking of those things, you limit your skills."

"It's whatever coach decides he wants to do with me, and I will be ready for the challenge," Ellington added.

RUCKER ADDED TO INJURY LIST

Defensive end Frostee Rucker (calf) was added to the injury list as limited and questionable Friday, joining four other players who are questionable for Sunday: guard Daryn Colledge (back), guard Earl Watford (knee), wide receiver Brittan Golden (hamstring) and linebacker Matt Shaughnessy (knee). Arians did say he expected everyone but Mendenhall to be ready to play.

For the Falcons, running back Steven Jackson is probable to play, but wide receiver Roddy White (hamstring, ankle) will not play. Also out are running back Jason Snelling (ankle) and linebacker Stephen Nicholas (thigh). Tackle Sam Baker (knee) and defensive end Akeem Dent (ankle) are questionable.