The thug punched Michael Avery before stealing his wallet and car keys and leaving him trapped in his bathroom.
He then fled the scene in Mr Avery’s Fiat Punto.
Retired lorry driver Mr Avery was alone in his home in Higher Walton, near Preston, on Tuesday night when there was a knock on the door.
The man shouted “Police, open up”.
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When he unlocked the door the raider barged in, pushing him into the bathroom.
Mr Avery’s daughter Michelle said: “I feel sick to my stomach.
“It was an appalling attack on a quite frail pensioner.
“He’s got a black eye and a thick lip but fortunately he’s not too badly hurt. He’s just shaken up.
“Without the car he will struggle to go out.”
Mr Avery said today he was not able to see who was at the door when he answered it.
By the time he had unlocked the door, he was pushed backwards.
He said: “He hit me a few times. He had no need to use that level of violence.”
The raider left him locked inside the bathrom after snapping off the handle.
A shaken Mr Avery managed to escape after about half an hour and raised the alarm.
He was taken to Royal Preston Hospital and treated for his injuries. including cuts and bruises.
Mr Avery said today he had now had spy holes fitted in his front door by a friend.
A Lancashire police spokesman said last night that a 48-year-old man and 41-year-old woman, both from Preston, were currently in custody being held on suspicion of robbery.