Wiesberger shot a second consecutive bogey-free 7-under-par 65 Saturday and moved to 14-under 202 after 54 holes.
Wiesberger, who started the day ahead by one stroke, opened Saturday's play with three pars but birdies at Nos. 4 and 6 allowed him to make the turn at 2-under.
He grabbed control, however, with a 5-under 31 on the second nine, posting birdies on each even-numbered hole. He made 10-foot putts for birdie at 10 and 12 and a 20-foot downhill putt at 14.
Wiesberger stuck his tee shot within 3 feet at the par-3, 189-yard 16th hole and chipped within 1 foot for an easy birdie at 18.