The Lions' 13-goal top scorer, who is poised to sign a new contract at The Den, suffered a muscle strain during the 2-1 defeat at Norwich on Tuesday night and will be sidelined for a fortnight.
Theo Robinson replaced Morison at Carrow Road and got on the scoresheet, so he is likely to start against Rovers.
Skipper Paul Robinson has resumed training following three weeks out with a hamstring injury and could return in defence.
Tony Craig is also close to fitness after a back problem but fellow defender Darren Ward and striker Josh McQuoid (both ankle) are still missing, along with suspended centre-half Jens Berthel Askou.
Source: PA
Source: PA