Asif Rehman, 20, admitted attacking 57-year-old William McKeeney but insisted: "I thought he'd get up."
Swearing on the Koran in his own defence, Rehman claimed he saw a "scuffle" between co-accused Adel Ishaq and Mr McKeeney.
Rehman said: "He fell back off the kerb and I kicked him about three or four times on the head.
"When I found out he had died next morning I couldn't believe it. I didn't think he would die."
Rehman and Ishaq, 19, both prisoners, are accused of the racially aggravated murder of Irish labourer Mr McKeeney outside his home in Pollokshields in January.
They are alleged to have repeatedly punched, kicked, stamped and jumped on his body, causing such severe injuries that he died hours later in hospital.
The High Court in Kilmarnock was shown pictures of a hat and a wrapped fish supper lying on the bloodstained, cordoned off street.
Advocate depute Tim Niven-Smith, prosecuting, told Rehman: "You were angry that night and the first person you saw was Mr McKeeney.
"The safety and sanctuary of his flat was only yards away.
"Mr McKeeney didn't stand a chance, did he? He had no defensive injuries.
"He didn't land a blow on you but you landed blows on him, didn't you? Rehman ageed, saying, 'yes'.
Mr Niven-Smith added: "You had no concern for the man you left dying in the street.
"Does that bring a lump to your throat?
"You showed no remorse for what you did. You didn't care whether Mr McKeeney lived or died."
Rehman denied this. The trial continues.