The 23-year-old Frenchman, however, pulled ahead of Donaldson with a 35-foot birdie putt on No. 17 and followed that up with another birdie on the final hole, closing out a round of 3-under 69.
He finished 72 holes at 24-under 264, two better than Donaldson, who fired the day's low round of 9-under 63 to charge into contention.
Dubuisson had never finished better than third on the circuit.
Rose bogeyed No. 18 for a 65, sharing third place with world No. 1 Tiger Woods at minus-20.
Woods (67) had made a late charge, birdying four of his last six holes at the Montgomerie Maxx Royal course.