Millwall skipper Paul Robinson is expected to be sidelined for five weeks with his latest injury.
The luckless centre-half made his comeback from a broken foot in the Johnstone's Paint Trophy defeat at Barnet last Tuesday, but lasted just 35 minutes before turning his ankle.
Although an X-ray showed no break, a subsequent scan revealed ligament damage.
Boss Kenny Jackett is scouring the loan market for reinforcements with 10 first-team players currently sidelined through injury.
But winger Lewis Grabban could return at Gillingham on Saturday after playing 90 minutes of the reserves' 1-0 defeat by Aldershot following an illness.