Lucas Herbert carded an excellent round of 64 to open up a two-shot lead over England's Tom Lewis on day three of the Portugal Masters in Vilamoura.
Oliver Fisher had made history in round two as he carded the first ever 59 on the European Tour and an unlikely eagle on the par four last would have handed Lewis the second on another low-scoring day.
A closing par saw Lewis sign for a 61 and a 17 under par total behind Australian Herbert, who is playing off invites this season as he looks to earn his full playing privileges on tour.
Lewis won this event in just his third start as a professional in 2011 and recorded a victory on the second-tier Challenge Tour just two weeks ago, although he looked unlikely to contend this week after an opening 72.
The 27-year-old has birdied 18 of his 36 holes since, including 10 in round three, and he admitted the thought of another 59 had crept into his mind.
"It's something that I noticed with three holes to go," he said. "I wasn't that bothered at the end of the day. I'm pleased that I shot 10 under par and put myself in there tomorrow. I can only continue to make birdies and see what happens tomorrow."
Herbert made eight birdies and a single bogey to get to 19 under, with England's Eddie Pepperell and Swede Marcus Kinhult four shots off the lead.
Fisher was then in the group at 14 under after taking 10 more shots than his historic effort on Friday.
Shane Lowry finished seven shots off the lead after a three under 68 to finish 12 under. That leaves him in 10th place.
Wicklow's Paul Dunne finished 6 under after an even par round of 71.