Cheltenham Town captain Shane Duff faces six months on the sidelines after undergoing an operation on his Achilles tendon.
Duff has been sidelined since the 5-4 home defeat by Bradford City in August and had initially hoped to be out for only four weeks.
However, after visiting a consultant earlier this week, the long-serving defender has gone under the knife and will be out of action until next year.
The injury leaves Cheltenham short of options at centre-half and Robins boss Martin Allen acknowledged it was a major blow to be losing Duff.
"Of course, this is a big blow for Shane and everybody at our club, especially in his testimonial year," Allen told the club's official website.
"Shane has been a top-class professional and this injury has plagued him for a while. Hopefully this operation will clear it up once and for all.
"I'm sure everybody will be hoping for a full recovery and would share my disappointment at losing such a good player, but we will face up to it and deal with it, as I have no doubt Shane will do."