Justin Rose made two eagles in his first five holes to catapult himself to the top of the leaderboard on day three of the Olympic Men's Golf Competition.
The Briton began the day four shots behind Marcus Fraser but as the Australian dropped a shot on the fourth, Rose was four under for his first five holes to get to ten under and open up a one-shot lead.
Belgium's Thomas Pieters was then at eight under, a shot clear of Grégory Bourdy and Henrik Stenson and two ahead of Kiradech Aphibarnrat, Graham De Laet and Bubba Watson.
Pieters gave a signal of his intent when he bombed his drive 379 yards down the first to help set up an opening birdie and join Fraser at the top of the leaderboard.
The two-time European Tour winner and Fraser both got in trouble off the tee on the second but while Fraser was able to save his par, Pieters dropped back to nine under.
That was only one ahead of Rose who - after starting birdie-bogey - holed a chip on the third for an eagle and, when Pieters three-putted the same hole, Fraser had a two-shot lead.
That cushion did not last long, however, as Fraser got into bunker trouble off the tee on the fourth to drop a shot with Stenson also making a bogey to drop to seven under.
Ahead at the par five fifth, Rose then hit the green in two and rolled in an 18-footer to take the outright lead while Bourdy also made a birdie.
Thailand's Aphibarnrat and American Watson were then at six under after they both made four birdies in their first five holes to turn in 31.
American Rickie Fowler set the clubhouse target at three under after turning in 29 as he signed for a brilliant 64.
Jaco Van Zyl followed Rose into the record books as he made the second hole-in-one in Olympic history.
The South African withdrew from The Open Championship and the US PGA Championship to focus on his preparations for Rio and he holed his tee-shot on the 173 yard eighth hole for the 30th ace of the European Tour season.
Rose became the first man in Olympic history to hole a tee-shot when he aced the fourth on Thursday.
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