Tuesday afternoon's Under-21 match between Sheffield Wednesday and Leeds United at Hillsborough was postponed after an unexploded bomb was discovered on the banks of the nearby River Don.
Roads around Leppings Lane were closed after the bomb was found by council workers carrying out a routine inspection of pipes.
A police spokeswoman said: "Officers are attending at the river bank of the River Don near Leppings Lane, Hillsborough, after being alerted by Sheffield City Council during a routine inspection of pipes to what is believed to be an unexploded device.
"Nearby roads will be sealed off while an inspection is carried out."
A date for the rearranged fixture has yet to be announced.
