President Robert Mugabe and old rival Prime Minister Morgan Tsvangirai set up a coalition government in February in an attempt to end a protracted political and economic crisis.
But their parties are feuding over the appointment of some senior state officials, sanctions and the pace of reform. And their credibility may hinge on whether they can resolve differences and secure regional and international aid.
Political analysts say Zuma — who is due in Harare on Thursday evening to meet members of the new unity government — may not be able to get Mugabe and Tsvangirai to agree on the disputes but will encourage them to keep talking.
Gwede Mantashe, secretary-general of South Africa’s ruling ANC, said Zuma is likely to take a tougher line on Zimbabwe’s political tensions than his predecessor Thabo Mbeki.
"The only difference is that Zuma will be more vocal on deviant behaviour," he said.
"There is no magic solution for the inclusive government, we have engaged parties and said ‘stay with the government’, walkouts are adolescent behaviour."
Zimbabwean Economic Planning and Development Minister Elton Mangoma, from Tsvangirai’s MDC party, told Reuters the unity government hopes for economic assistance for Zimbabwe, which needs about $10 billion in reconstruction funds.
"They are our largest trading partner and we hope discussions, at the highest level, will help us forge closer ties on the economic front," said Mangoma.
Mangoma declined to give details of how much aid Zimbabwe was hoping for, but state media reports this week said Harare was seeking an additional $50 million in credit from South Africa, which has already provided a similar amount.
Zimbabwe has so far managed to secure almost $2 billion in credit lines from African states and institutions to revive private firms, but has failed to attract budgetary support.
Western donors have demanded broad political reforms before committing any financial aid to Zimbabwe’s new government.
Tensions have been rising in the unity government, with the parties trading blame over the slow pace of reform and accusing each other of undermining the power-sharing agreement brokered by Mbeki.
Analysts say Zuma had shown signs he could take a tougher stance on Zimbabwe, a departure from the approach by Mbeki, accused by critics of siding with Mugabe.
While Tsvangirai’s MDC has said it hopes Zuma’s visit would help clear some sticking points in the political pact, Mugabe’s spokesman George Charamba on Thursday downplayed expectations.
"What we know is that President Zuma is a guest of the Zimbabwean government and has come to officially open the agricultural show," Charamba told the state-controlled Herald newspaper.
"We are also aware that matters to do with the global political agreement fall under the purview of the facilitator, who is comrade Mbeki."
Tsvangirai accuses Mugabe of refusing to implement an agreement to reverse the appointments of central bank governor and the Attorney-General, as well as plotting to reduce the MDC’s parliamentary majority through the arrest and prosecution of several of the party’s lawmakers.
Mugabe’s ZANU-PF has countered this by demanding that the MDC lobby for the lifting of sanctions imposed by Western governments on Mugabe and his inner circle.
Charamba said that the issue was likely to feature prominently in discussions with Zuma.
"The one thing that is going to hit President Zuma in the face are the continued sanctions on Zimbabwe and the need for unanimity on strategy inside and outside Zimbabwe…," Charamba was quoted saying.