Following up his first tour win last week at the Joburg Open, Grace became just the sixth golfer to win his first two European Tour events in back-to-back tournaments.
Tied with former Major winners Els and Goosen on 12-under-par 280, it went to a sudden-death playoff where the 23-year old made a two-putt birdie on the par-five 18th, the first playoff hole, while Els and Goosen only managed par.
"It's a dream come true to win such a big event - pretty much the best tournament I've played in so far", Grace said after his victory at the Fancourt in South Africa.
Despite an impressive third round that saw him share the lead with Grace, Belgian Nicolas Colsaerts bogeyed the last to finish in fourth place on 11-under-par 281. Master's Champion Charl Schwartzel ended the tournament in fifth on 10-under-par 282.
Europe's Ryder Cup captain José María Olazábal failed to end his seven-year drought and, despite starting well with two birdies giving him a share of the lead, slipped back to sixth, finishing on eight-under-par 284.
