Parkhead fell silent on Wednesday night as thousands of supporters realised a life-or-death drama was taking place in the stands.
Teams of stewards and medics could be seen surrounding 66-year-old fan Robert Coyle who had collapsed, with one paramedic conducting intensive treatment to halt a heart attack.
Bizarrely, the game between Celtic and Hearts went on and a stretcher had to be carried around the pitch rather than directly across it.
But Hoops websites were yesterday filled with messages of disgust, accusing their opposite numbers of chanting “You’re not breathing anymore’’ at the fallen fan.
One contributor to the Kerrydalestreet site, Renfrew Bhoy, wrote: “If I could see what was going on, trust me, the Hearts fans could see too.
“I can also confirm they were singing; ‘You’re not breathing any more’ when the guy was on the ground.’’ Another fan, Paulo 1986, wrote: “Seething doesn’t begin to describe how I feel inside at the behaviour of the Hearts fans.
“I can only pray for the poor guy and his family. It’s not a nice sight seeing young kids being led out of a game due to circumstances like that happening in front of them.’’
The normally raucous ‘Green Brigade’ section called a halt to their tunes and their drummer put down his drum as the medical emergency unfolded.
After treatment lasting at least 10 minutes, Mr Coyle from the nearby Carmyle area, was carried to a waiting ambulance and transferred to Glasgow’s Royal Infirmary.
Many Hoops fans then raised their scarves, clapped their fellow fan out of the ground and sang “You’ll Never Walk Alone.’’
Yesterday, his condition was described as “serious but stable’’ as he fought for life in the hospital’s intensive care unit.
A Celtic spokesman said the club had been “inundated” with inquiries about the condition of the long-standing season ticket holder.
He added: “The thoughts of the players, management and everyone at the club are with Robert and his family at this time.’’