Connor Minto initially though he'd been hit by a stone, but then a horrified friend saw there was a .22 air rifle pellet lodged in his forehead, just above his left eye.
Bleeding profusely, the boy, from Chester-le-Street, County Durham, rushed to find his dad and was taken to the Royal Victoria Hospital in Newcastle, where the pellet was removed and he received stitches.
Three 14-year-old boys have been arrested in connection with the incident and bailed pending further inquiries.
Connor had been playing in the match when he was substituted and so stood on the sidelines.
His mum, Kerry, told her local paper: "He felt like he had been hit by a stone so he turned to his friend and asked him what had happened.
"His friend said told him he had a bullet in his head. At that point he didn't know it was a pellet, so he told us he thought he was going to die.
"Physically he has recovered from the incident but mentally he is terrified. He is scared to go out and he now sticks by me or his dad's side.
"I dread to think what could have happened if it would have been an inch or so lower - it would have changed his whole life.
"I think a lot of people aren't aware how dangerous air rifles can be. It's important that children are not left unsupervised with them."
Detective Constable Andy Froggatt, said: "This was a very serious incident. It could have been much worse if the pellet had hit the Connor's eye.
"Thankfully Connor is recovering well now, but he was extremely upset by what happened.
"We are appealing to anyone who was at the football or rugby games that were being played on Saturday and witnessed the incident to contact police."
Anyone with information is asked to contact DC Andy Froggatt on 101, or call Crimestoppers anonymously on 0800 555 111.
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