England captain John Terry may miss the friendly with Switzerland on 6 February after breaking three bones in a foot.
Chelsea defender Terry went off after a challenge with Eboue
The Chelsea defender, 27, limped off in Sunday's 1-0 defeat by Arsenal after a challenge with Emmanuel Eboue.
Club doctor Bryan English told Chelsea TV: "I would imagine he will be out for a minimum of six weeks."
The injury to his right foot is ill-timed for Terry, with new England coach Fabio Capello refusing to confirm whether he will continue as skipper.
Eboue caught Terry after leaving his foot dangling when he overran a ball, which the Blues centre-back cleared.
"An X-ray taken immediately after John left the field did not show the injury," added English.
"The fractures, which include his third metatarsal, were revealed following scans performed on Monday afternoon."
Terry's expected period on the sidelines would mean he would only just be returning to action a week before the encounter with Switzerland - England's first match under Capello.
John will be a big loss and is very important to the squad
Chelsea striker Salomon Kalou
The Chelsea captain returned from a knee problem and cheekbone injury on 24 November against Derby after nearly seven weeks on the sidelines.
He missed England's final Euro 2008 qualifier against Croatia in November as the national team failed to earn the draw they needed to reach next summer's finals.
But Terry helped Chelsea beat Derby and played in five games when the Blues remained unbeaten before the loss at Arsenal.
Chelsea striker Salomon Kalou has revealed that his Ivorian compatriot Eboue apologised to Terry for the challenge.
Kalou was unhappy with Eboue's tackle but 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," stated 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."
Grant already has Terry's regular central defensive partner Ricardo Carvalho and striker Didier Drogba on the sidelines.
But he could welcome back midfielder Michael Ballack, who hasn't played since April after two operations on his left ankle, for Wednesday's Carling Cup quarter-final against Liverpool.