Immelman, who opened the final round three strokes off the lead,
made a 12-foot birdie putt on the final hole of regulation to complete
a round of 5-under 67 and move into tie with Clark at 14-under 274
at Erinvale Golf Club.
Clark missed a 10-foot birdie putt on the final hole of
regulation and settled for 3-under 69.
On the playoff hole, Immelman hit his second shot from 169 yards
to within 6 inches.
"I saw the people in the stands jump up and clap and I just
kept hoping that it would be a tap in," Immelman said.
Clark missed his birdie try, and the 23-year-old South African
tapped in for his first victory, worth $200,000 and a two-year
exemption on the European Tour.
"I don't know how to describe how happy I am with this win. So
many times over the years, I have walked down the 18th fairway and
allowed myself, for a moment, the dream of winning this
tournament," Immelman said.
"This is the greatest way to start the year."
England's Justin Rose closed with a 1-under 71 and finished in a
tie for eighth place.