The Blitzboks triumphed in the first four – in Dubai (2), Malaga and Seville – but finished in a tie for seventh in Singapore and fifth in Canada to see their lead trimmed to just six points.
It’s a three-team race for the title this season between South Africa (111), Argentina (105) and Australia (100).
The remaining legs are scheduled for Toulouse (20-22 May), London (29-29 May) and Los Angeles (27-28 August).
Teams are awarded 22 points for a win, 19 for second, 17 for third, 15 for fourth, 13 for fifth, 12 for sixth and 10 each for seventh and eighth, down to a single point for 16th and last place.
