CINCINNATI -- The Bengals still aren't exactly sure when injured Pro Bowl receiver A.J. Green will be rejoining their ranks, coach Marvin Lewis said Friday afternoon.

After Green's visit to a foot specialist last week in Cincinnati, the hope was that the third-year star wideout would be back after this week. But the possibility exists his return could take a little longer.

The Bengals aren't sure when A.J. Green will get back on the field. AP Photo/Al Behrman

Asked Friday about a more defined timetable for Green's return from a big toe injury that kept him out of last week's game and will do the same this Sunday, Lewis simply said "the time is up in the air."

When the Bengals travel to Indianapolis on Sunday, Green will be missing his second start this season. In addition to not playing these last two games, Green also missed nearly all of the Week 2 game against Atlanta when he removed himself after just six plays because of pain in the toe. Before these injury woes, Green had only missed one game in his first three seasons.

Green has been around the team all week but he hasn't been seen with his teammates during the open portions of the Bengals' practices. Lewis said he wasn't requested to attend the workouts because there was no need for him to stand around on his toe for two hours. Lewis added that he can detect where Green's inability to play has been frustrating him.

"It's hard enough for him not to be out there at practice with his teammates," Lewis said. "He was on the sideline on Sunday [versus the Panthers] and it was rough for him. It was rough. He stood there before the game at the stretch lines with his arms folded. It's a difficult time for him not to be able to play.

"He's such a competitive person -- so inwardly, quietly competitive -- so it's hard."

In addition to Green, the Bengals also have been without receiver Marvin Jones, the player who was projected in the offseason to be the No. 2 pass-catching threat behind Green. Earlier this week, the Bengals placed Jones on season-ending injured reserve. Tight end Tyler Eifert also has been on short-term IR since Week 1, causing the Bengals' passing options to be shared among a group of mostly backup receivers, running backs and other tight ends.

Green has played three complete games this season. He has 17 catches for 314 yards and two touchdowns.