Sarah Jane Smith is the best-placed of six Australians after the opening round of the LPGA Tour's Kingsmill Championship.

Smith fired a four-under par 67 to hold down a share of fifth place, two shots behind American leader Lexi Thompson (65) at Kingsmill Resort's River Course.

After making birdies at three of her opening four holes, Smith dropped a shot at the sixth.

But she steadied on the back nine with successive birdies at the 15th and 16th holes.

Su Oh made a similar start with birdies at the first, second and fourth holes before carding a three-under par 68 in a bogey-free round.

Minjee Lee had four birdies and a bogey to be in a tie for eighth place with Oh.

Karrie Webb and Katherine Kirk both shot even-par 71 while Sarah Kemp had a three-over par 74.

New Zealand's Lydia Ko responded to the heat on her world No.1 ranking by unfurling a near-flawless opening round.

Ko shares also fifth place after opening with a four-under 67.

A bogey at the sixth hole spoiled a round which featured five birdies.

Ko hasn't won a tournament since July, putting her 19-month reign as atop the rankings under serious threat this week.

Her opening round eclipsed that of her nearest pursuers for the top spot.

AAP

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