The Gunners winger pulled up in the 23rd minute immediately after firing in a low cross at Crystal Palace in Saturday's late kick-off.
Saka hit the deck, where he could be seen holding the back of his right leg.
An Arsenal medic came to his aid, but the 23-year-old was unable to shake off the knock, and was swiftly replaced by Leandro Trossard.
talkSPORT reporter Ian Abrahams revealed on commentary duty that Saka looked emotional as he walked towards the tunnel, describing him as 'distressed'.
Gooners and boss Mikel Arteta will be left sweating over the severity of the suspected injury during a hectic festive period.
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Saka has started all but one of Arsenal's 17 Premier League matches so far this season.
The England international has also started in five of the club's Champions League fixtures, along with one Carabao Cup fixture.
More to follow...