That news came as Green -- who left practice during warm-ups on Wednesday after aggravating an injury to his right big toe -- had his right foot in a walking boot during Friday morning's walkthrough.
Green was officially listed as questionable on the Bengals injury report that was released Friday afternoon, along with receiver Marvin Jones.
On Thursday morning, during his weekly interview with SiriusXM Radio, coach Marvin Lewis told host Ross Tucker that Green's injury was "a little more than" turf toe. Three weeks ago, Green told reporters in Cincinnati that the issue was "something like turf toe, but not as bad." He played in that Week 3 game against the Titans after playing just six plays the week before.
Lewis isn't yet sure whether the injury could affect Green beyond this week's game.
"It's day to day, as I was told [Friday]," Lewis said. "He's feeling good. Which is a good thing, a positive thing."
Green's injury dates back to the Bengals' season opener, when the Pro Bowl wideout injured his toe during the first quarter of Cincinnati's 23-16 win over Baltimore. Green continued to play through the pain, though, and ended up catching a 77-yard go-ahead touchdown in the fourth quarter.
After removing himself six plays into the Week 2 game against the Atlanta Falcons, Green didn't have any issue with the injury until Wednesday afternoon. Just after the Bengals concluded their stretching and plyometrics, Green took his right cleat off and slammed it and his helmet to the ground in obvious frustration. After chatting briefly with Lewis, Green got onto a cart and was driven off the practice fields by a trainer and across the street to Paul Brown Stadium for observation.
Green had further evaluation by an area foot specialist Thursday.
Jones hasn't practiced since last Monday, when he tweaked an ankle two practices after returning from a broken foot. He and Green were observers Friday morning as the rest of the Bengals practiced.
With both unavailable this week, the Bengals will be forced to turn to other receivers Sunday.
"We have a lot of guys who can fill the void of A.J. and with Marvin not being there," one of those receivers, Mohamed Sanu, told ESPN.com. "They're huge voids, but we've got guys that can play. The whole room is very good, and it's deep, and we know we've got guys who can play ball. So we're going to go out and do our best and execute the way we can."
Green has 17 receptions -- tied for the team lead with Sanu -- for 314 yards this season.