Schwartzel, finished 5-under par for the round and was 13-under 203 for the tournament, two shots clear of Finch.
Schwartzel, who hails from South Africa, turned in his second-consecutive bogey-free round at the Leopard Creek Country Club. He strung together consecutive birdies on the eighth and ninth holes and again on 12 and 13.
Finch was also flawless en route to a 67. The Scotsman birdied the final hole to finish with his best round of the event.
Victor Riu (67) was third at 10-under at the end of the day. Third-round co-leader Morten Orum Madsen careened to a 7-over 79 for the round and tumbled into a tie for 34th place at 1-under 215.