Everton have confirmed that defender Michael Keane suffered a small hairline fracture of his skull in the 2-2 draw with Bournemouth on Saturday.
Keane scored the Toffees' second goal at the Vitality Stadium, but was later rushed to the nearby Poole Hospital after an injury-time clash of heads with team-mate Idrissa Gueye.
After being monitored overnight, a statement from Everton the following day confirmed the centre-back would miss a minimum of three to four weeks with the injury.
Keane, who had started Everton's first three games of the season under new manager Marco Silva, is now expected to be on the sidelines for Wednesday's Carabao Cup tie at home to Rotherham as well as the Premier League fixtures against Huddersfield and West Ham.
He later thanked Everton's medical team and staff at Poole Hospital for their support following the incident: 'Thank you to everyone for all the well wishes and support.
'I'm okay but suffered a small hairline fracture of the skull which will heal itself and means I won't be able to have any head contact for three to four weeks.
'I will be back with my team and back on the pitch as soon as I can after that.
'I also want to say a huge thank you to the medical staff at Everton and Bournemouth as well as all those at Poole Hospital for their excellent treatment and care.'
On the pitch, Everton squandered a 2-0 lead at the Vitality Stadium following goals from Theo Walcott and Keane.
Josh King's penalty was followed up by Nathan Ake's close-range equaliser in a fiery game that saw Richarlison and Adam Smith both handed straight red cards.