Broncos forward Alex Glenn.

Brisbane are facing an injury crisis in their forward ranks, with second-rower Alex Glenn and rookie bench prop Payne Haas set for extended time on the sidelines.

Glenn has a grade two medial ligament injury which could see him out for a month while Haas suffered a dislocation of his shoulder during the crushing 38-24 loss to Manly at Suncorp Stadium.

The injuries to Glenn and Haas are compounded by international stars Josh McGuire (ankle) and Matt Gillett (neck) already being unavailable.

Coach Wayne Bennett confirmed Haas had a dislocated shoulder and was "a tough kid" to insist on playing on after sustaining the injury in the first half.

Haas did not return in the second half and Glenn left the field late in the second half with a knee injury.

"They (medical staff) are talking a grade two, so it is probably a month," Bennett said when asked how long Glenn would be out.

As for who would replace the duo Bennett said "I don't know what my options are right now."

Bennett conceded his side was outplayed and defended poorly.

"We got off to a pretty ordinary start, got ourselves back into it and then gave it all up again," Bennett said.

"We get some progress and then we regress... after a pretty good month. We were pretty good in Newcastle, had our moments against Melbourne and then won two other games. The fifth week we are not consistent enough."

Bennett has put faith in young forwards Tevita Pangai jnr, Jaydn Su'A and Matt Lodge, who are now all playing big minutes with McGuire and Gillett out.

"That is part of the problem but that's the reality. We are lacking some experience there right now and each week it multiplies," he said.

"Each week these [young] guys have got to get up but they are not used to being up every week. They haven't played enough football...but you can't use that as an excuse."

Bennett did not blame his halves Anthony Milford and Kodi Nikorima for the defeat.

"When we defend like tonight...those guys aren't going to be the difference," he said.