A man accused of killing a teenager has told a court he punched him because he thought he was about to be struck himself.
Reece Hornibrook, 17, died of a brain injury two days after being hit in Saddlebow Road, King's Lynn, on 7 July.
Liam Russell, 32, who denies manslaughter, said he argued with Mr Hornibrook over a broken wing mirror.
He told Norwich Crown Court he was walking away when the teenager came towards him with clenched fists.
The court heard Mr Russell's BMW was damaged in the early hours of the morning, while he was out.
Mr Russell, of Metcalf Avenue, King's Lynn, said he arrived home to find Mr Hornibrook shouting at his wife, adding that the teenager "rammed at me with his head and put it straight into my face".
He told the court: "I thought I was about to be struck because of how quickly he came to my left hand side.
"Both of his hands were clenched. I threw a punch at him."
William Carter, defending, asked Mr Russell: "Did you want to cause serious injury?"
He answered: "No."
He said he felt "dreadful" and "devastated" by Reece's death.
Earlier this week, Stephen Spence, for the prosecution, argued Mr Russell was not acting in self defence but had "lashed out in anger".
The trial continues.