The 34-year-old Zindzi gave an interview to the glossy Thandy magazine published yesterday that her mother still loved Mr Mandela, but that they did not see each other any more, "as if they don't exist for each other".
Even if he wishes to divorce his estranged wife, Mr Mandela is having trouble enough sacking her from her post as a deputy minister after allegations of bribe-taking.
Her remarkable resistance has marked her out as a tough leader of the populist faction that has brought the ANC into a slough of allegations of sleaze.
Using legal tactics honed in the days of apartheid, she has temporarily blocked a police investigation into documents seized from her house and offices. Until that is cleared up, she refuses to meet the deputy president, Thabo Mbeki, who is in charge of seeing whether she should be sacked.
Zindzi Mandela's frank account of their life make strains seem unsurprising. She is probably the person closest to Winnie Mandela, and is alleged to have shared in the rough justice meted out by her mother during the late Eighties in Soweto.
"I am something of a rebel," she admitted. Her four children each have a different father. One faded away, one stabbed her and another was a militant who "hanged himself in his cell" according to a dubious police report at the time.
"I never knew a normal life," Zindzi said. "The day I buried the father of my child, my own father was released from prison." Her fourth child is by her businessman husband, Zwelibanzi Hlongwane.
Mr Mandela has written of falling in love with Winnie at first sight, and Zindzi blamed intense public pressures after his release for the failure of the two to rebuild their relationship.
"They never could talk things over. From the day my father was free, we had to share him with the rest of the world," she said. "The sad thing is that nobody realises that my father is very lonely."
n Zindzi and her husband, a senior leader of the ANC, are being sued for non-payment of furniture bills. The couple allegedly owe more than £12,000 for furniture already delivered.