Alex Iwobi left the field in tears after suffering an injury in a tackle with Tyrell Malacia on Friday evening.
The Nigerian midfielder was stretchered off after seeming to injury his ankle in a challenge from the Dutch left-back, handing manager Frank Lampard a hefty injury blow.
The Toffees take on Southampton next after their 3-1 defeat to Manchester United on Friday – which saw banners unfurled calling for the board to be sacked – as the pressure continues to build on Lampard after a string of poor results.
With the sides locked at 1-1 after the break at Old Trafford, Everton looked to put early pressure on the hosts in the FA Cup third round tie.
However, as Iwobi chased a long ball through on the right-hand side of the pitch as part of an Everton counter attack, he was tackled by Malacia.
The challenge did not result in a free-kick for the Toffees, with the former Feyenoord defender winning the ball cleanly in the tackle.
The damage was done after the midfielder went over his ankle, and he was in clear and evident pain on the field.
His team-mates rushed to surround him and ascertain the severity of the injury, with club captain Seamus Coleman one of the first to the scene to assist his colleague.
The former Arsenal star was quick to indicate his discomfort, and the Toffees’ medical team rushed on to the field as he covered his face with his shirt.