The 72-hole stroke-play tournament marks the halfway stage of an already eventful summer leg of the Sunshine Tour.
Ernie Els' dramatic last-minute victory in the Vodacom Players' Championship in December was matched by a fairytale win for Clark in the Bell's South African Open at Durban Country Club a week ago.
McNulty, winner of the 2001 South African Open, returns to Woodhill Country Club as the man who dominated last season's summer tour, with the dapper Zimbabwean claiming three tournament victories and a record seventh money-winning title.
But the field is also laced with a few worthy contenders for the title.
One of these is local boy Martin Maritz, who returns to his hometown hunting a victory that has been threatening over the last couple of weeks. Maritz was in contention for last year's PGA title, but fell short with a 71 on the final day to finish joint third.
The young professional has also been in fine form of late, contending for both the Vodacom Players' Championship in December, where he finished tied for second, and following that up with a top-10 finish in the South African Open.
'My victory in the Nelson Mandela Invitational convinced me that I can compete with some of the best golfers and beat them,' said Maritz.
'It's all a learning experience for me at the moment. But as long as I keep putting myself in a position to win tournaments, then it will happen sooner or later.
Cape professional Nicholas Lawrence completes the list of hopefuls. Lawrence achieved his best-ever finish of a tie for fourth in November's Zimbabwe Open.
Deane Pappas will not be back to defend his title. Pappas is competing alongside his brother Brenden on the PGA Tour after both secured their tour cards through a top-15 finish on the Buy.Com Tour's money-winning list last year.