Arsene Wenger has revealed that Per Mertesacker's ankle injury "does not look too good" after the defender limped out of Arsenal's FA Cup semi-final win over Reading on Saturday.
The Gunners' stand-in skipper was replaced by Gabriel Paulista on 63 minutes and Wenger admits to being downbeat over his prognosis.
"He has an ankle problem. He is limping badly so that doesn't look too good," the Frenchman told the club's official website.
The reigning champions advanced into the final with a 2-1 extra-time win over the Championship club at Wembley.
Goalkeeper Adam Federici allowed Alexis Sanchez's 105th-minute shot to squeeze through his legs and trickle over the line to inflict heartbreak on Reading, who have never reached an FA Cup final.
Sanchez had earlier fired the Premier League side into a half-time lead, before Garath McCleary cancelled it out.
The North Londoners will face either Liverpool or Aston Villa in the final, with the pair poised to square off at Wembley on Sunday.
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