The midfielder picked up the issue during Sunday’s pre-season game with Chelsea and he underwent a scan on Monday.
The initial diagnosis is not as bad as first feared, with the hope being that Partey will only be out for a few weeks.
The Ghanaian is due to see another ankle specialist this week and he will have further tests to see what damage has been done to his ligaments.
Either way, the expectation is that Partey will miss Arsenal’s opening game of the Premier League season at Brentford on August 13.
Arsenal then have matches against Chelsea and Manchester City before the international break in September.
It remains to be seen if Partey will be able to play in those games, with an update likely later this week.