Oldham striker Charlie MacDonald has been ruled out for four to six weeks with a torn thigh muscle.
The tear comes as a blow with MacDonald, 32, only returning to action recently following an ankle problem.
"It is very disappointing to lose Charlie, especially at such a busy time of the season," manager Lee Johnson told the League One side's website.
With fellow forward Kirk Millar also sidelined with calf and ankle injuries, Johnson may bring in a another striker.
The transfer window for loan signings has shut, but clubs can still bring in players who are free agents.