Everton defender Michael Keane was taken to hospital after clashing heads with team-mate Idrissa Gueye in Saturday's draw with Bournemouth.
The England international was taken off on a stretcher in injury time of the 2-2 draw at the Vitality Stadium following a delay of approximately six minutes.
The 25-year-old centre-half was given oxygen on the pitch after the collision in the air with Gueye left him motionless on the pitch.
After the game Everton manager Marco Silva confirmed: "He went to the hospital. I don't have more updates about the situation.
"When he went to the hospital, in that moment he looked a little bit better, in better condition as well.
"I hope everything is okay now but we have to wait."
New loan signing Kurt Zouma replaced Keane after he was stretchered off.
Earlier Keane had put Everton 2-0 ahead with a header in the 66th minute, following Theo Walcott's opening goal 10 minutes earlier.
Two late goals from Joshua King - from the penalty spot - and Nathan Ake secured a point for Bournemouth in a game that saw Richarlison and Adam Smith sent off either side of half-time.