Everton have confirmed Bernard has suffered medial ligament damage after leaving the field injured against Brighton and Hove Albion on Saturday.
The club's medical staff will now liaise with a knee consultant in the coming days with grade two damage revealed following scans.
Bernard left the field after less than half-an-hour with a knee injury that was seemingly sustained after a slip on the turf.
The 27-year-old managed to hobble off the pitch, with the help of Everton officials, but was in some discomfort with television replays making for concerning viewing.
Bernard left the Amex Stadium with a crutch and his leg in a soft brace and will now miss Tuesday's Carabao Cup fourth round clash against Watford.
