A source told ESPN.com's John Clayton on Monday that the wide receiver has a partially torn labrum in his left shoulder. The team had said the injury, which occurred in a preseason game on Aug. 17, was a sprained shoulder.
The source said that Johnson is expected to wear a harness but may be able to avoid surgery and play this season. The same source said that Browns tight end Kellen Winslow played last season with a similar injury.
The Bengals were also without Pro Bowl receiver T.J. Houshmandzadeh in the game when Johnson was injured. He missed his second preseason game with a sore hamstring.
The Bengals don't have much experience at receiver behind Johnson and Houshmandzadeh. Marcus Maxwell started Sunday in Houshmandzadeh's spot. The Bengals released No. 3 receiver Chris Henry after his latest arrest in the offseason but re-signed him last week. He is suspended for the first four games of the season.
With the Bengals hurting at the position, sources with NFL teams said on Monday that the Bengals have called offering
running back Rudi Johnson in a trade for a legitimate receiver.
A Bengals source told ESPN's Chris Mortensen, however, that head coach Marvin Lewis was "totally unaware" of any attempts to trade Rudi Johnson, but he didn't rule out that president and general manager Mike Brown directed the calls.
"Who knows?" the source said. "Right now, a lot of teams are calling each other with all kinds of what-if trade scenarios."
Chad Johnson, who had 93 catches for 1,440 yards and eight touchdowns last season, landed awkwardly in the game against Detroit and was in obvious pain. He was examined on the field before heading to the locker room. The team initially said that X-rays and an MRI were negative.
Chad Johnson had lobbied for a trade during the offseason but eventually backed off and reported to training camp. He was limited, however, while recovering from surgery to remove bone spurs from his right ankle.
Senior writer John Clayton covers the NFL for ESPN.com. Information from The Associated Press was used in this report.