Chelsea will be without captain John Terry for well over a month after scans revealed that he suffered three broken bones in his right foot in the 1-0 defeat at Arsenal.
Terry was injured by a late challenge from Gunners midfielder Emmanuel Eboue during Sunday's showdown at the Emirates Stadium and subsequent scans on the problem have revealed serious damage.
Club doctor Bryan English told the club's official website: "Scans have revealed that John Terry has fractured three bones in his right foot, including his third metatarsal.
"The initial diagnosis suggests he may be out for six weeks.
"An x-ray taken in the Arsenal medical room straight after John left the field didn't show the injury.
"However, as is usual with mid-foot injuries, the fractures were revealed following scans, which were performed on Monday.
"John will start his rehabilitation immediately with the Chelsea medical team and we will continue to monitor the injury."