Cape Town - Reed ends title drought at Northern Trust
SA's top ranked golfer Oosthuizen lies 28th in the FedEx Cup standings and will need to maintain his spot to advance through to the final top-30 shootout at the season finale Tour Championship.
The 2010 Open Championship winner carded 69 in the final round of this past weekend's Northern Trust to end tied for sixth on 12-under 272.
Frittelli currently sits 60th in the FedEx Cup standings following his T43 finish this past weekend in New Jersey.
The 29-year-old is the only South African to win on the PGA Tour this year when he lifted the John Deere title.
Meanwhile, Branden Grace missed the Top 70 cut - finishing 77th in the FedEx Cup standings - despite ending T30 at the Northern Trust.
PGA Tour FedEx Cup Playoffs:
Northern Trust - 125 golfers (August 8-11)
BMW Championship - 70 golfers (August 15-18)
Tour Championship - 30 golfers (August 22-25)