Rochdale have confirmed Reece Gray dislocated his ankle and fractured his leg during the recent friendly against Liverpool.
Gray went down in the 55th minute of the behind-closed-doors run-out, with his injury forcing the game to be called off.
Dale physio Andy Thorpe revealed the club are not sure how long the 19-year-old will be sidelined.
He told Rochdale's official website: "Reece fell awkwardly, resulting in him dislocating his ankle and fracturing his tibula. He has also suffered soft tissue damage.
"He was taken straight to hospital where he had an x-ray and had his leg put in plaster.
"He'll require surgery due to the nature of the fracture and we expect this to take place later in the week."