Having taken part in a limited session on Thursday, Green did not practice at all on Friday, casting major doubt over his availability for Sunday's clash at Lucas Oil Stadium.
Green is still under the concussion protocol after taking a hit from Pittsburgh Steelers safety Mike Mitchell in Week 17.
In order to play on Sunday, he needs to pass the league's concussion protocol, including clearance from an independent neurologist.
He has been officially classified as 'doubtful' for the fixture.
If the 26-year-old is ruled out, the Benglas will travel to Indianapolis without him for the second time this season, the first resulted in a 27-0 shutout in Week 7.
James Wright is unavailable due to a knee injury while Dane Sanzenbacher is out for the season with concussion, potentially leaving Bengals coach Marvin Lewis just four receivers to choose from this weekend if Green cannot recover.