"It is going to be an interesting day‚ hold on to your seats. My view is that it’s very difficult to call at this point‚" said Kaon Capital CEO Luke Alers.
Whoever wins the race will most likely be the face of the party when it contests general elections in 2019.
The market’s perception is that a Ramaphosa victory would deliver economic reforms and help stave off further sovereign rating downgrades.
A Dlamini-Zuma win is perceived as maintaining the current economic status quo‚ which has increasingly been criticised for veering off fiscal consolidation path.
At 9.31am‚ the rand was at R13.0754 to the dollar from R12.9651‚ at R15.3889 to the euro from R15.2362‚ and at R17.4520 to the pound from R17.2759.
The euro was at $1.1769 from $1.1745.