Arsenal goalkeeper Jens Lehmann will miss the next two weeks after aggravating an Achilles injury while on international duty with Germany.
The veteran keeper played 90 minutes of Wednesday's friendly with England before returning to Arsenal for an assessment on the injury.
And Lehmann, who has made a series of errors in the opening weeks of the new season, will now be out of action until September.
He will miss the second leg of the Gunners' Champions League qualifier against Sparta Prague and the home clash with Portsmouth.
"Jens is out and he will miss two weeks, I think. Maybe more. I don't know," admitted Gunners boss Arsene Wenger.
"He is going to see a specialist in Germany. He had this injury before but it has got much worse."
Wenger will now use Manuel Almunia in place of the his regular number one, while summer signing Lukasz Fabianski will provide back-up.
Lehmann has come under fire for gifting Fulham striker David Healy a goal in the early minutes of Arsenal's 2-1 victory on the opening weekend.
He also allowed David Dunn's shot to slip through his hands during last weekend's 1-1 draw with Blackburn Rovers at Ewood Park.