Gregory McCalium, 24, was punched twice in the face after breaking into the home of Frank Corti.
The OAP said he was compelled to defend himself and his wife after McCalium threatened them at their home in Botley, Oxford.
McCalium had thrown a knife at the pensioner – which missed. At that point the 72-year-old used his boxing skills to stop the would-be attacker in his tracks.
“I had to restrain him before he could go and get the knife,” Mr Corti told the Oxford Mail.
“I was scared when he first threw the knife, but most people would have acted in the same way.
