BOURBONNAIS, Ill. -- The first major injury of Chicago Bears training camp occurred at a position where the team could least afford it -- No. 3 wide receiver.

Coach Marc Trestman said last week that 2013 seventh-round draft pick Marquess Wilson led the battle for third receiver behind Alshon Jeffery and Brandon Marshall.

On Monday, Wilson went down in practice with a broken collarbone.

"I'm extremely disappointed," Trestman said. "He was continuing to ascend. That's football, unfortunately."

There was no immediate timetable for Wilson's return, but players often return from such an injury in the same season. Last year, Packers quarterback Aaron Rodgers broke his collarbone against the Bears in Green Bay at midseason and then came back at the end of the year to beat Chicago at Soldier Field in a game to decide a playoff berth.

Losing Wilson as the Bears did made it all the more aggravating. He was laying out for a pass in the end zone on a deep route in a meaningless scrimmage play.

"That's the hardest part about coaching in practice," Trestman said. "You hear us say it all the time: stay off the ground, stay off the ground. And diving for balls is one of the most difficult things not to do when you're a competitive player.

"We promote (not diving), we talk about it a lot. But from my experience, it's very difficult to stop. When a guy goes to make a play for the ball, you're not going to be disappointed with him if a guy doesn't go to the ground."

Wilson admitted it was instinctive.

"I look back at it, and I probably shouldn't have done it, but it just happened," he said.

Wilson was having one of his better practices in a series of them.

"He's been showing it consistently making plays," Bears tight end Martellus Bennett said of Wilson. "Back in the day, he was a flash player. But he's been working so hard, and he's been stepping up, so those are going to be some hard shoes for us to fill because he's been doing a great job."

Bennett said Wilson, who worked out extensively with Marshall and Jeffery in the offseason, understood the offense to the point that he was helping line veterans up on some plays.

"Another guy has a chance early in camp to step up to find out who that guy is going to be," Bennett said.

The problem is identifying the replacement.

Eric Weems is one possibility. Like the rest of the candidates, he isn't ideal. Weems has only 27 catches in six seasons because he is largely considered a special teams player. He's also 5-foot-8, 182 pounds. Wilson is 6-3.

"Eric is not just a returner," Trestman said. "He's a very good receiver in terms of route-running. Quarterbacks trust him. He plays bigger than his size. He's got a big catch radius."

Former Redskin and 49er Josh Morgan is on the team but hasn't made much impact in practices, and neither has veteran Josh Bellamy. Armanti Edwards and Micheal Spurlock were viewed more as return men when signed.

Recently signed Dale Moss had some big practice days and fits in as a 6-3 receiver, while return man Chris Williams can catch but is very undersized at 5-8, 175.

As long as the Bears have both Marshall and Jeffery healthy, and Bennett at tight end, as well as one of the game's best receiving running backs in Matt Forte, they appear capable of functioning for at least a while without a high-level third receiver.

Backup tight end Dante Rosario also is making an impact in camp. He made only one catch last year but didn't go through training camp with the Bears before joining them in the second week of the 2013 season, so Chicago is capable of going with two tight ends more often.