Inbee Park retained her lead in the women's golf competition at Rio 2016, but Lydia Ko carded a sublime six-under 65 to close on top spot, the world number one's round including a hole-in-one moments after Lin Xiyu made history with a first women's Olympic ace.
Seven-time major winner Park led by one stroke from Stacy Lewis following Thursday's play, but the latter endured a torrid third round - signing for a five-over 76 at the Rio Golf Centre.
As windy conditions made life difficult for the competitors, Park mixed six birdies with five bogeys to lead by two strokes at 11 under.
New Zealander Ko is in a tie for second with Gerina Piller of the United States (68), with Shanshan Feng of China (also 68) three off the pace.
The highlight of Ko's day came when she aced the eighth, while four front-nine birdies enabled her to turn in 29.
Nine pars followed on the tougher inward nine, keeping her firmly in contention heading into Saturday's final round.
Lin also made a hole-in-one at the eighth, before Ko, her crisp strike bouncing twice before landing in the cup.