Gillingham defender Callum Davies will be out for at least three months after suffering an ankle injury during his loan spell at Dover Athletic.
The 21-year-old centre-back was forced off during Dover's 1-0 win over Cheltenham in the FA Cup 10 days ago.
Davies, who signed a new deal until 2016 at Priestfield Stadium in October, will have surgery next week.
"It's an old injury that flared up again," Gills boss Peter Taylor told the club website.
Davies joined Dover on loan last month and made three appearances during his time at Crabble.
"I knew he wasn't match fit to play League One football but I never thought he wouldn't last the loan at Dover," added Taylor.