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.
Millions of Getty images now available for free via embed tool
NBC reportedly holds celebs hostage to Jimmy Fallon's show