Upper Darby police say 33-year-old Stephen Campbell told them he forgot the infant was in the car while he watched the game Sunday.
The Delaware County Daily Times reports police were dispatched to the field around 3:30 p.m. and that Campbell came running to them with the baby in his arms.
Police Superintendent Michael Chitwood says the baby was in the car for about 45 minutes, but was found conscious and alert. She was treated and released to her mother.
Campbell faces charges including simple assault and endangering the welfare of a child. A message left at a telephone listing for him wasn't immediately returned.