Eric Garcia was taken from the field on a stretcher late in Manchester City's 3-0 Premier League win over Arsenal after a nasty collision with team-mate Ederson.
Brazil goalkeeper Ederson rushed out of his own penalty area to make a clearance and completely wiped out his team-mate, who appeared to be hit in the face.
City's medical team quickly raced onto the pitch to attend to a prone Garcia on the Etihad Stadium pitch.
The 19-year-old Spanish centre-back was eventually taken away after a lengthy stoppage, as several of his City team-mates looked on concerned.
Pep Guardiola's men were 2-0 up at the time of the injury thanks to goals from Raheem Sterling and Kevin De Bruyne, with Phil Foden adding a third against 10-man Arsenal when play resumed.