Webb trails fellow Australian Lindsey Wright, who had a 72 Saturday to lead the tournament at 3 under, and is tied with South Korea's Shin Ji-yai at 2-under 217 overall.
Teenage amateur Kristie Smith, who led at the halfway point but struggled with a 4 over in the third round, and England's Melissa Reid were another stroke back in at 1 under.
Webb, seeking a fourth national title, was relying on her experience to get her through the last round at Kingston Heath.
'There's players up there who haven't won the Australian Open and I have,' Webb said. 'I do have experience at winning golf tournaments.
'I don't know if that necessarily counts for too much, but I know that I have a great chance to win.'
Webb recovered her round after getting into trouble on the fourth hole, when she pulled her second shot and landed in a greenside bunker. From there, she hit into unplayable rough, took a penalty, chipped on and two-putted for a seven.
'It was completely out of my control,' she said. 'There was about a millimeter of sand under my ball, there was nothing I could do.'
She had a birdie two holes later and had two more on the first three holes of the back nine to grab a share of the lead before a bogey 5 on the 18th dropped her to second place.
Shin began the day two shots off the lead in second place and shot a 74 that included three back-nine bogeys, one of them at the end that cost her a share of the lead.
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