Wiesberger began Saturday's round tied for second place but moved to the top of the leaderboard with his second straight 6-under 65 and three-round score of 13-under 200.
Wiesberger steadily parred the first seven holes but birdied six of the next seven holes before finishing at par on the final four.
Fisher limped along on a sprained ankle to a 2-under 69 Saturday. His up-and-down round included five birdies and three bogeys, including one on the 18th hole, which gave Wiesberger sole possession of the lead.
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