Smylie birdied his first two holes to move clear at 12 under but Smith, who also birdied the first, then drew back level with another birdie on the third.
Marc Leishman, in the last group with Queenslanders Smith and Smylie also picked up a stroke on the third to be 10 under with David Micheluzzi.
Jason Day hits a tee shot in the final round as he attempts to chase down the leaders. (Jono Searle/AAP PHOTOS)
Smith is chasing a fourth Kirkwood Cup but first title in more than a year while 22-year-old Smylie, a recipient of three-time champion Smith's scholarship five years ago, won the WA Open last month.
There was plenty of movement below them on Sunday in what has become a three-round event due to excessive rain.
Spain's Angel Ayora was seven under through 15 holes to reach nine under, level with the morning's other big movers Anthony Quayle and Lukas Nemecz.
Defending champion Min Woo Lee carded a final-round 66, finishing at seven under after just surviving the cut on an inconsistent Saturday.
Nick Voke has the clubhouse lead at eight under after shooting a six-under 65.
Jason Day, in his first Australian appearance in seven years, birdied his first and fifth holes to sit inside the top 10 at eight under and still within reach of the leaders.
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