The veteran Frenchman dropped shots at the first and third but birdied the long sixth, then sunk putts of eight and 12 feet for gains at the eighth and ninth.
Hebert added another birdie on the 16th to sign for a joint-best-of-the-week 64 and set the clubhouse target at 12 under.
“I played fantastically well,” he said. “I used a lot of irons off the tee to try to keep the ball in play, because if you find the rough out there you sometimes don't have a chance to go for the greens.”
Olesen birdied the tenth and 11th to advance to 16 under, but Wiesberger, Levet and Bland kept the pressure on by all moving to 13 under.