Su Oh heads the Australian charge at the LPGA Classic in Grand Rapids, but faces a big challenge with several in-form stars lurking at the top of the leaderboard.
Canadian teenager Brooke Henderson fired an eight-under 63 in the first round on Thursday to sit alone on top, but included in a six-way tie one shot behind are fellow major winners Lexi Thompson, Shanshan Feng and Stacy Lewis.
Oh carded a four-under 67 to be among a group of 12 players in a tie for 13th.
One shot further behind is Australia's seven-time major winner Karrie Webb, with compatriots Sarah Jane Smith (two under) and Sarah Kemp and Katherine Kirk, both on one under.
The 19-year-old Henderson eagled the par-five eighth hole and had six birdies in her bogey-free round at Blythefield.
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She won the major KPMG Women's PGA Championship last year and has three tour victories.
"I felt great from the start," Henderson told reporters.
"Everything was going my way. I was hitting the ball really well and some putts were dropping, which (was) kind of a change from the past few weeks.
"I had a really good feeling and made a lot of birdies, a lot of putts. I feel my game is in a really good place."
Kiwi Lydia Ko, who lost her at No. 1 ranking in the world after an 85-week run at the top, returned from a three-week layoff to post a six-under-par 65 to be joint eighth.
New world No. 1 Ariya Jutanugarn opened with a two-under 69. She won the LPGA Classic on Sunday in Canada in a playoff with Thompson and In Gee Chun.
