Donaldson had back-to-back birdies three times in the third round, against just one bogey, in reaching 16-under 200 for the tournament.
Stenson, whose round included a double-bogey at the par-5 ninth, turned in a 69 Saturday.
Donaldson led Moore and Stenson by three after Friday's play but, while Moore was steady with a bogey-free round, it was Bjorn who put the pressure on Saturday. He was 3-under at the turn and jumped to 6-under on the day with an eagle at the par-5 10th and a birdie at No. 9.
Donaldson had birdies at Nos. 4 and 5 and again at 10 and 11 to keep Bjorn back. Bjorn slipped with a bogey at 14 -- another par 5 -- while Donaldson posted birdies at 14 and 15. Donaldson did give back a stoke at the par-4 17th. It was just his second bogey of the week.