Davis sets men's pace at Australian Open whille 16-year-old leads women's
Australian teenager Rachel Lee was a shock joint leader, upstaging major winners Shin Ji-yai, Minjee Lee and Hannah Green.
The qualifier fired a six-under-par 67 to accompany South Korea's Jenny Shin at the top of the leaderboard.
Former champion Davis sunk seven birdies and an eagle in front of big crowds at the DP World Tour event in Sydney to put the Australian one clear of US PGA Tour player Patrick Rodgers.
The mixed Australian Open involves men and women teeing off in alternating groups on the same courses.
The Jack Nicklaus-designed Australian Golf Club is the main venue across all four days, with the nearby Lakes Golf Club co-hosting play for the first two rounds.
Australian Hayden Hopewell and Scotland's Connor Syme were tied third in the men's tournament on seven-under.
"I know this place well, so I felt like I had plenty of good memories in the bank to go out there and play the course with," said 2017 winner Davis of the Lakes Golf Club.
Australia's Min Woo Lee, who won the Australian PGA Championship in Brisbane last week, continued his stellar form with a bogey-free 67 as he chases a fourth DP World Tour title.
"I felt like I left a couple out there at the end, but bogey-free, solid," said Lee, who has reached a career high 38 in the world rankings.
Japan's Rikuya Hoshino, who came second in Brisbane, carded 68.
Frustrated Smith
But former world number two Cameron Smith has work to do after a 71 on the back of missing the cut a week ago in Brisbane by nine shots and being reduced to tears.
Smith, who plays on the Saudi-backed LIV Golf circuit, said he felt his game had improved after four birdies and three bogeys.
"A little bit frustrating, but it was better," he said. "I think there's definitely something to build on there."
Last year's champion Adrian Meronk of Poland hit 73 while American Michael Block, who became a cult hero at this year's PGA Championship with a hole-in-one playing alongside Rory McIlroy, made 71.
In the women's event Rachel Lee and Jenny Shin finished one ahead of two-time British Open champion Shin Ji-yai who shot a five-under 68.
Tied for fourth on four-under were Australia's Stephanie Kyriacou and South Africa's defending champion Ashleigh Buhai.
Australia's world number five Minjee Lee was tied sixth on three-under par.
"I tried my best out there, shots were solid, putting was solid and everything was pretty good out there for me," said Rachel Lee, who had a practice round with her "hero" Shin Ji-yai this week.
"I'm surprised at how strong she is," Shin Ji-yai, an 11-time winner on the US LPGA Tour, said of the co-leader. "I'm looking forward to watching her in future."
Green was six off the pace while Japan's Ayaka Sugihara, who drained a hole-in-one on the par-three 11th at the Australian Golf Club, ended eight adrift.