Arsenal's Brazilian midfielder Edu is facing up to six weeks on the sidelines with a broken toe.
Edu, who has only just recovered from a calf injury, suffered the injury in Tuesday's 3-1 Carling Cup win over Everton at Highbury.
Gunners manager Arsene Wenger said: "He has a broken bone in a toe on his right foot - it's the bad news of the night."
Edu was the most senior player in an Arsenal team featuring the club's clutch of promising youngsters.
And Wenger believes the future of the club is in safe hands after his team romped to victory over Everton.
He said: "It's not only that we qualified, but that we did it in style and we love doing that.
"This team has quality and it shows the future of the club is in good hands.
"I was pleased we didn't panic at 1-0 down. After that, it was a good
mixture of enthusiasm and quality. They played intelligently, technically well
and with the spirit we like to play the game."