Brandon Stone posted a third consecutive 66 to take a two-shot lead into the final round of the Portugal Masters.
The South African mixed six birdies with a sole blemish at Dom Pedro Victoria Golf Course to get to 15 under and pull clear of compatriot Dean Burmester and overnight leader Oliver Fisher.
Stone started the day two off the pace and slipped further behind with a three-putt bogey at the third, only to make a two-putt birdie at the par-five fifth and roll in from six feet at the eighth to reach the turn in 34.
The three-time European Tour winner followed a 20-footer at the 11th by holing a birdie from even further out at the par-four next to move top of the leaderboard, before extending his advantage with back-to-back birdies from the 16th.
Burmester followed a front-nine 31 with birdies at the 12th and 15th to briefly lead, before bouncing back from a bogey at the par-three 16th to pick up a shot at the next on his way to a third-round 65.
Midway leader Fisher - who carded the first 59 in European Tour history at last year's event - is also on 13 under, with the Englishman recovering from making three consecutive bogeys from the fifth to fire four birdies in a row from the 12th.
Steven Brown, starting the week 148th on the Race to Dubai, kept hopes of retaining his card alive after a six-under 65 lifted him to fourth spot, with Jeunghun Wang tied-fifth alongside South African trio Haydn Porteous, Justin Walters and George Coetzee.
Matt Wallace bogeyed the final hole for the second day running, with a five-under 66 leaving him alongside Eddie Pepperell and defending champion Tom Lewis in the group five off the pace.
Who will win the Portugal Masters? Watch the final round live on Sunday from 12.30pm on Sky Sports Golf!