Chelsea captain John Terry has broken three bones in his foot and could be out for up to six weeks.
England skipper Terry left the Emirates Stadium on crutches, after being forced off in Chelsea's 1-0 defeat by Arsenal yesterday following a challenge by Emmanuel Eboue.
'Scans today have revealed that John Terry has fractured three bones in his right foot, including his third metatarsal,' said a Chelsea statement.
'The initial diagnosis suggests he may be out for six weeks.'
Club doctor Bryan English told Chelsea TV: '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 this afternoon.
'John will start his rehabilitation immediately with the Chelsea medical team and we will continue to monitor the injury.'
Blues striker Salomon Kalou earlier revealed Eboue apologised to Terry for the challenge which left him on crutches and facing Christmas on the sidelines.
Kalou revealed he spoke to his Ivorian compatriot Eboue after yesterday's game.
And Kalou, who was unhappy with Eboue's tackle, praised the Gunners player for at least offering an apology.
'I was saying to Eboue that it was a red card because he did it on purpose - but he denied that,' said Kalou.
'He said he tried to block the ball and it was not on purpose. He said sorry to John. He didn't mean to do it, but to apologise was a nice thing to do.
'John will be a big loss and is very important to the squad. We will miss him and it will be difficult to do it without him but we have the players to do that.'
Goalkeeper Petr Cech held his hands up after his role in Arsenal's winner, when he failed to claim the ball and allowed William Gallas to head the winner.
Understandably, the Czech Republic goalkeeper is keen to move on and forget the incident as soon as possible.
'It is difficult and for me I am disappointed because, in the end, the game was decided by my mistake,' Cech said.
'It was a mistake from me. There is no explanation or excuse. It was as simple as that.
'This is part of the game. You play in these big games with this passion. These are the best games to play in and you always want to do your best.
'I love this type of game, but will not remember this one as one of the best ones.
'You have to analyse yourself and see why you made a mistake, what was the moment you could have done better.
'Of course you have to watch it, but in the end you have to turn the page and go on.'