An initial scan revealed possible cartilage damage in a big setback for the defender who missed out on the end of last season and the World Cup with a fractured metatarsal in his left foot.
Also absent for Sunday's clash with Inter Milan at the Lane are Jermaine Jenas (hamstring), Andy Reid (foot strain) and Paul Stalteri (twisted ankle). Anthony Gardner is fit to return after recovering from a shin injury.
"Ledley is out with suspected cartilage problems and he could be out for six to eight weeks," reported Martin this afternoon. "It is a big blow for us.
"Andy Reid will out for another two to four weeks and Paul Stalteri is making progress, but will be out for another week. Jermaine Jenas has a hamstring injury and will miss this game.
"Calum Davenport will play in place of Ledley, while Anthony Gardner is fit again and will be on the bench."
Martin Jol will be without the services of Ledley King for six to eight weeks after the captain sustained a knee injury in training.