"At this point anything is an option," Rivera said following Tuesday's practice. "What you're hoping is you can get him on the football field and we'll see once the doctor gets a chance to look at him."
Stewart, who's battling back from surgery on both ankles, is continuing to work with trainers on the side but is keeping a close eye on the plays being run during practice.
He has yet to practice with the team.
Rivera said the sixth-year NFL running back will meet with team physicians soon — though he isn't sure exactly when — to determine if he's close to being ready to return to the practice field.
DeAngelo Williams has been taking reps with the first team and rookie Kenjon Barner has seen increased action in his absence.
As for the Sept. 8 season opener against Seattle, Rivera doesn't know what to expect.
"You'd love to have him but we'll have to wait and see how it goes," Rivera said. "It's going to take a little time."
Stewart has turned down several interview requests to talk about his injury. He has battled ankle, foot and toe problems since entering the league as a first-round draft pick out of Oregon in 2008.
And while Stewart takes some good-natured ribbing from teammates for all of the practice time he's missed through the years — he's sat out much more than he's practiced — he was pretty reliable up until last season when it came to playing games.
He'd played in 71 of 73 games in his career prior to landing on injured reserve the final seven games of last season with what the team described as a high ankle sprain.
Stewart said at the start of training camp he had surgery on both ankles earlier this offseason but didn't give a timetable for his return.
I never knew he had surgery on BOTH ankles in the off season, thank you so much Hurney for not putting a injury clause in NONE of the contracts. To be honest with you, I'm ready to move on from D-will and Stewart, and I think Gettle will make drastic changes to our backfield next year.