The Hoops youngster suffered a hefty blow to the head when challenging midfielder Nuri Sahin during his side's 2-0 friendly defeat against the Spanish giants in Philadelphia
The 19-year-old is thought to have suffered a fractured jaw after colliding with Nuri Sahin when challenging for an aerial ball.
The Scot's unconscious state was quickly flagged up by players of both sides, resulting in medical staff rushing on to the pitch before taking him off the field wearing a neck brace.
"Dylan McGeouch has been taken to hospital with suspected jaw fracture," Celtic confirmed on their Twitter account.
Sahin, meanwhile, issued a public apology to the Hoops player via his own Twitter account after the match.
He posted: "@DMcGeouch get well soon my friend, i am so sorry, fingers crossed!"