A man who who attacked a former cancer patient in an argument over a disabled parking space killed him "in a moment of madness", a court has heard.
Alan Watts, 65, of Biggleswade in Bedfordshire, is on trial at Luton Crown Court for the manslaughter of 64-year-old Brian Holmes after having an alleged row in a supermarket car park on August 3.
Mr Holmes, from Sandy in Bedfordshire, died at Addenbrooke's Hospital in Cambridge the day after the confrontation in the car park of the Biggleswade branch of Asda.
Just days before the incident, he had been told he had beaten cancer.
Watts has pleaded not guilty to manslaughter, claiming self-defence.
But crown prosecutor Ann Evans told the court during her opening address that Watts goaded Mr Holmes after seeing his car was parked in a disabled park before setting on him in an unprovoked attack.
Ms Evans said Mr Holmes had returned to the car without his wife Christine, who suffered rheumatoid arthritis, when Watts - who had parked him in - sarcastically shouted: "You look like you need a wheelchair".
Ms Evans said: "This is a case about how a moment of madness can change people's lives forever.
"The defendant, Alan Watts, in a show of extraordinary violence, lashed out at Brian Holmes at a car park in Asda and killed him with a punch to the head."
Ms Evans said CCTV footage, which she played to the four women and eight men in the jury, showed Watts punch Mr Holmes twice in a "right-left combination" before the victim dropped to the ground.
Watts then gets back in his vehicle and drives away, she said.
Mrs Holmes struggled to compose herself from the public gallery as the footage was being played while Watts, who was wearing a large headphones to help him hear the proceedings, sat motionless.
Ms Evans said Watts had told police he was acting in self-defence because Mr Holmes had tried to pull him out of his car and had grabbed his wrists.
The prosecutor said Watts claimed Mr Holmes was "effing and blinding" and suspected he was drunk.
Watts told police he left the scene immediately because he wanted to get his wife home and "didn't know whether he was going to be attacked again", Ms Evans said.
But the prosecutor said it would be up to the jury to decide whether it was reasonable to believe Mr Holmes was the aggressor, particularly given he had recently received positive medical news.
"Here is Mr Holmes, a man who was recently given the all clear from cancer," she said.
"Does he, as Mr Watts suggest, lose it?"