Fleetwood is just behind on 13 under with another South African Dean Burmester.
A win by either Rose, second in the points standings before this tournament, or leader Fleetwood would guarantee either the Race to Dubai title and the $1.25 million bonus.
Rose would also win by finishing second, assuming he is ahead of Fleetwood, and could still claim the end-of-season accolade by finishing as low as fifth if he finishes higher than his compatriot.
Rose's only other order of merit triumph was in 2007 but he has posted wins in his past two tournaments.
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Another superb round on Saturday included a chipped birdie at the par-three 13th and a 45-foot birdie at the 16th.
Rose saved par on the last despite taking a penalty drop, pitching to seven feet and rolling in a testing right-to-left putt for par which kept him one clear of Frittelli, who had birdied four of the last five holes in a flawless 63.
"There's a hunger and motivation there," Rose said. "It's about playing good golf tomorrow. With a one-shot lead, there's no strategy. It's about playing well tomorrow."
Rose withstood a stiff test of his nerve by Fleetwood who, after a poor first day, has fought back with successive 65s, including eight birdies in his last 11 holes on Saturday.
Others took advantage of helpful conditions and 15 players are within five shots of the lead, including Sergio Garcia, who is 10 under par and could still win the Race to Dubai if he wins the tournament and his rivals falter.
Overnight leader and defending champion Matthew Fitzpatrick shot a level-par 72 to drop back in the field.
(Reporting by Neil Robinson, editing by Ed Osmond)
