The reigning Bell's South African Open champion still heads the race after finishing tied for eighth in the Dimension Data Pro-Am last weekend. Clark aims to win the money list and claim the lucrative exemptions into the World Golf Championships American Express Championship and the British Open.
But Clark will have his job cut out in this week's event on the KwaZulu-Natal south coast.
Rose, who claimed his maiden European Tour victory in the Dunhill Championship at Houghton Golf Club, climbed into third place on the current money list, roughly 150,000 South African rands ($13,000) behind Clark.
Rose still has a distinct chance of overtaking Clark in the tight run for the title with Dimension Data champion Retief Goosen out of the running. Goosen, second on the current money list, returns to London for a well-deserved rest after his two recent victories.
A victory at the Nashua Masters could prove a vital check in light of the R317,000 ($27,400)on offer in the Tour Championship next week. If Rose can consistently outperform Clark in these two events, then his chances of topping the Order of Merit are strong.
The 156-man field at the scenic Wild Coast Sun Country Club will also feature defending champion Mark McNulty.
Although McNulty has struggled so far this summer, he showed an improved form at last week's Dimension Data Pro-Am at Sun City with a joint 11th finish.
Darren Fichardt, Bradford Vaughan and runner-up in the Dimension Data Pro-Am, Scotland's Scott Drummond round off a quality field for the penultimate event on the summer leg of the tour.
2001/2002 Sunshine Tour Order of Merit (Earnings in South African Rand)
1Tim Clark (RSA)
2Retief Goosen (RSA)
3Justin Rose (ENG)
4Martin Maritz (RSA)
5Steve Webster (ENG)
6Mark Foster (ENG)
7James Kingston (RSA)
8Ernie Els (RSA)
9Jonathan Lomas (ENG)
10Roger Wessels (RSA)
11David Park (WAL)
12Darren Fichardt (RSA)
14Simon Dyson (ENG)
19Paul McGinley (IRL)
26Scott Drummond (SCO)
27Mark McNulty (ZIM)