Mbeki brokered the power-sharing deal that brought Zimbabwe’s long-time President Robert Mugabe together with his erstwhile rival Morgan Tsvangirai, who became prime minister in a unity government in February.
Under the joint administration, Zimbabwe has halted its spectacular economic collapse, abandoning its worthless currency and easing price controls, which has brought food back onto store shelves.
But with unemployment at 94 percent and more than half the population surviving on international food aid, the country remains mired in a humanitarian crisis that shows few signs of easing.
Squabbling within the unity government is rife, most dramatically between Finance Minister Tendai Biti, one of Tsvangirai’s top aides, and central bank chief Gideon Gono, who presided over years of world-record hyperinflation.
"South Africa was instrumental in the negotiations for the powersharing government and they will support it" despite the problems, said Joseph Kurebga, a Harare-based political analyst.
But South Africa’s stake in the success of the government goes well beyond diplomacy.
Up to three million Zimbabweans have fled to South Africa in hopes of earning a living, while a cholera epidemic that erupted last year quickly seeped across the border.
Mbeki dealt with challenges though his so-called "quiet diplomacy" that avoided calling out Zimbabwe on its failures. Zuma is unlikely to prove so gentle, analysts said.
‘He may have a few surprises in store …’
"They are going to maintain this idea of constructive engagement with the leadership in Zimbabwe, trying to get them to come together around the table and resolve whatever issue might arise," said Siphamondla Zondi, researcher at the Institute for Global Dialogue.
"But I don’t think that they are going to have patience with the Zimbabwean players should they not move along as expected."
Zuma has proven himself a capable negotiator, credited with curbing political attacks between his own African National Congress (ANC) and the Zulu-dominated Inkatha Freedom Party in the 1990s.
As the crisis unfolded in Zimbabwe last year, Zuma didn’t hesitate to speak out, saying that he believed Zimbabweans were demanding change and that delays in the violence-plagued elections were "unacceptable".
"What we saw from Mr Mbeki was a kind of silence about the violence in Zimbabwe," said Isabella Matambanadzo, Zimbabwe programme director for the Open Society Initiative for Southern Africa.
"Zuma is a very smart political animal," she said. "He may have a few surprises in store in terms of the leadership style he’s going to establish in the region, and in particular in trying to build a leadership style that is credible to the people of the region."
But with the unity deal already in place, Zimbabwe is unlikely to dominate Zuma’s concerns when he is faced with a sagging economy and pressing demands to save jobs and fight poverty at home, analysts said.
Takavafira Zhou, a political scientist at Zimbabwe’s Masvingo State University, said domestic affairs would demand more of Zuma’s attention than the affairs of neighbours.
"Zuma has enough problems on his hands to embark on a robust foreign policy," Zhou said. (Sapa-AFP)