South Africa's president is headed north to try to help feuding members of Zimbabwe's coalition government resolve their differences.
Thursday's trip comes amid rumors that Zimbabwean President Robert Mugabe is ill.
But South African presidential spokesman Vincent Magwenya said Wednesday that "everything's on track" for President Jacob Zuma to meet Mugabe and Zimbabwean opposition leader turned Prime Minister Morgan Tsvangirai.
Tsvangirai's party accuses Mugabe's ZANU-PF party of stalling on reforms and continuing to attack and harass opposition activists.
ZANU-PF says Tsvangirai's party should be pushing harder to get the international community to lift sanctions against Mugabe and his top aides.