C-Jay Hall, 13, from Thursley Crescent in New Addington, was playing on the skate ramps outside the Timebridge Centre last Thursday with a friend when a girl came into the park with a puppy and full grown dog, thought to be a pit bull.
Before the owner could call him away he started to attack C-Jay, who tried to fight him off with his scooter.
"I was so scared – the pain was shocking," he said. "My only thoughts were trying to get the dog off. I kept trying and trying but he wouldn't leave me alone."
His mother, Rebecca Carey, said: "The dog just bit on his thigh and wouldn't let go. He and his friend were trying to push him off and then the owner grabbed the dog and told C-Jay to run.
"He ran out of the park but the dog kept catching up with him, he bit him again and again and dragged him to the ground twice.
"He had to run across the road and almost got run over but again the dog got there first. It wrestled him to the ground and was just biting and biting. He even bit into his calf muscle."
C-Jay feared he would never escape the fearsome attack when he heard a resident call him from across the road. They had seen the furore and told him to run into their house. As he did so the dog continued to chase after him and had to be kicked back out of the door by the resident.
An ambulance and police were called, as was C-Jay's mum.
"He was in hospital for three days and had to have a four-hour operation to fix the puncture wounds," said Ms Carey. "He had 101 stitches and was on morphine the whole time he was in hospital because he was in so much pain. When I got home I looked at the tracksuit and there were chunks of C-Jay's flesh stuck to the rips in the material."
C-Jay is now off school and has told his mother he is too scared to go out and play with his friends. Speaking of the dog he told the Advertiser: "I want it put down."
The animal is now understood to be in custody but police had not commented on the incident at the time of going to press.
(This is Croydon - June 23, 2012)