FAYETTEVILLE -- The news regarding Marcus Monk's right knee could have been a lot worse, but it still wasn't what Arkansas football coach Houston Nutt wanted to hear.

Monk, who decided to return for his senior season, is expected to miss at least 4 to 6 weeks after the wide receiver underwent arthroscopic surgery Monday to repair cartilage damage in his right knee.

Monk will not be ready for the Sept. 1 season opener against Troy University, and Arkansas athletic trainer Dean Weber said it would be difficult to accurately predict when the wide receiver will be able to get back on the field.

"Hopefully, he will be able to return in approximately four weeks. I emphasize the word hopefully," Weber said following Monday's evening practice. "We'll just see how it goes."

Initially, Nutt thought Monk would only miss a few days of practice after an MRI on Friday came back negative. But doctors discovered during Monday's surgery that Monk's knee had suffered more damage than originally believed.

Weber said Monk had a small tear in the posterior horn of the lateral meniscus repaired during the surgery. The senior also had an articular cartilage fracture of the lateral femoral condyle.

"This is pretty unusual," Weber said, describing the injury. Weber stressed, though, that no ligament damage was discovered.

Monk injured his right knee during last Thursday's practice when he was hit hard from behind by free safety Michael Grant after catching a pass. The injury was originally described as a bone bruise.

Weber said Monk will begin an "aggressive rehabilitation," though Weber noted that another update on Monk's injury won't come for another two weeks.

"It could have been a lot worse, that's what I'm thankful for," Nutt said. "I'm thankful that we have a chance to get him back (this season). ... It could be much worse; you could be talking about ligaments (torn)."

Monk's injury puts more pressure on Arkansas' unproven wide receiving core. Coaches had been looking for a No. 2 wide receiver to step opposite Monk, and now the other receivers will be called upon to produce immediately.

Arkansas wide receivers coach Alex Wood said Monday that senior Robert Johnson, junior Reggie Fish and sophomores London Crawford and Lucas Miller are being considered to help make up for the loss of Monk.

"We have to do it now. There is no later, no another week, no another couple days of practice. It's now," Johnson said. "The season is coming up soon; we have to be ready to play."

Monk was easily Arkansas' leading receiver last season, catching 50 passes for 962 yards and a school-record 11 touchdowns.