Coetzee triumphed by three shots on 19 under, at Royal Johannesburg and Kensington Golf Club in the co-sanctioned European and Sunshine Tour event.
After 24 top 10 finishes on the European Tour, it was his first win on the circuit to cap off a number of consistent performances recently for the 27-year-old.
The Pretoria golfer began the year ranked 98th in the world.
Coetzee was the only big mover on the rankings of the top South African players. Charl Schwartzel remained at 18, Louis Oosthuizen dropped from 30 to 34, Ernie Els dropped one place to 35 while Branden Grace climbed one position to 47.
– Sapa
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