Charlton have confirmed that goalkeeper Rob Elliot has sustained a groin tear that will require around one month of rehabilitation.
The shot-topper suffered the injury during Saturday's 2-2 draw against Gillingham at The Valley and had to be replaced at half-time by Darren Randolph.
Physio Steve Allen has since assessed the extent of the problem and League One promotion-chasing Charlton will be without Elliot for around four weeks.
Allen told the Addicks' official website: "Rob suffered a tear to his left groin which got progressively worse during the first half, and he will be out for around a month."
Boss Phil Parkinson will also be without striker Deon Burton for a fortnight after he suffered a knee ligament injury
Akpo Sodje, Lloyd Sam and Jose Semedo also picked up knocks against the Gills and could be doubtful for Saturday's vital trip to Huddersfield.