The former Valencia defender will not play in the finale after limping off at Wembley last weekend
The Germany international was forced off during the closing stages of last weekend’s semi-final victory against Manchester City and sat out the Premier League clash with Aston Villa three days later.
Gunners boss Mikel Arteta said he “doubted” Mustafi’s chances of being fit for the showpiece final during his news conference on Thursday, and his fears have now been realised.
Having spent the week assessing the severity of the injury, the club’s medical team have now come to the conclusion that he will play no part in the clash with the Blues on August 1 at Wembley.
The news will come as a blow to the Gunners as Mustafi has re-established himself as a key player under Arteta, having fallen out of favour under his predecessor Unai Emery.
The 28-year-old had started nine of Arsenal’s last 10 matches prior to Saturday’s game against Pep Guardiola’s side at Wembley, after making just one Premier League start during the first half of the campaign under Emery.
Mustafi’s injury is likely to present an opportunity for Rob Holding to stake a claim for a cup final spot. The former Bolton player replaced Mustafi in the starting line-up for the midweek defeat at Villa and is likely to keep his place for their final Premier League game of the campaign against relegation-threatened Watford on Sunday.
There was some better news on the injury front for Arsenal, with confirmation goalkeeper Bernd Leno will resume full training next week after recovering from a knee injury.
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However, scans revealed the injury was not as serious as first feared and the club were always confident he would return in a matter of weeks rather months.
Despite his return to fitness it remains to be seen whether he will be considered for the FA Cup final, with his understudy Emiliano Martinez impressing in his absence.