Arsenal defender Gabriel Paulista has been ruled out for six to eight weeks with an ankle injury.
The 25-year-old was stretchered off during his side's final pre-season fixture on Sunday, with manager Arsene Wenger later confirming that he had sustained ligament damage.
The Brazilian has now been ruled out for up to two months, leaving Arsenal short in defence going into their Premier League opener against Liverpool on Sunday.
Per Mertesacker is not expected to play again until next year due to an injury of his own, while Laurent Koscielny only returned to training on Monday following an extended break after Euro 2016.
Calum Chambers and new signing Rob Holding are now Arsenal's most likely centre-back pairing at the Emirates Stadium this weekend.
The Gunners have been strongly linked with a move for Valencia's Shkodran Mustafi, though, with the North Londoners understood to have made a £30m bid for the Germany international.
