Marcus Fraser turned in 33 to re-establish his three-shot lead on day two of the Olympic Men's Golf Competition in Rio de Janeiro.
Heavy rain had made it difficult for the early starters and none of them could reel in the Australian who had set a brilliant pace with an opening 63 on Thursday.
Thomas Pieters and Henrik Stenson had both cut the gap to one shot but some dialled-in iron play allowed Fraser to make birdies on the third and fifth to become the first man to get to ten under this week.
Pieters and Stenson remained his closest challengers, with Grégory Bourdy in the clubhouse at six under after a 69, and Justin Rose also at that mark after 12 holes as European Tour Members dominated the top of the leaderboard.
The rain started at around 8.45am but was beginning to relent in the early stages of Fraser's round and the Maybank Championship Malaysia winner put approaches to three and two feet to make his gains.
Belgian Pieters got off to a flying start as three quick birdies catapulted him up the leaderboard.
The two-time European Tour winner made a birdie on the first and then played a wonderful bunker shot on the second to set up another gain.
He had driven the green at the third on day one for a birdie and a 326 yard tee-shot left him a short wedge in and helped him to a birdie-birdie-birdie start. He then parred his way to the turn.
Sweden's Stenson also got off to a brilliant start, taking advantage of the par five first and then holing a remarkable 60-foot putt on the second after flying his second shot over the back of the green.
The 40 year old then made an incredible par on the next after putting his tee-shot in the water, holing his putt from 108 feet.
Finding a bunker off the tee on the next then led to a bogey but he walked in a 27-footer on the eighth and was seven under after 11 holes.
Bourdy holed a 14-footer on the third and took advantage of the par five fifth but bogeys on the seventh and 11th had him back to square one for the day. The closing holes present birdie opportunities, though, and the Frenchman made gains on the 16th and 17th.
Briton Rose was also at six under with two birdies in 12 holes courtesy of an excellent bunker shot on the fifth and tee-shot to 13 feet on the next.
German Alex Cejka, Canada's Graham DeLaet and Swede David Lingmerth were then at five under, a shot clear Ireland's Seamus Power and Cheng-tsung Pan of Chinese Taipei.
