Oliver Fisher took a one-shot lead into the weekend at the Portugal Masters after a second successive 65 at Vilamoura.
Englishman Fisher carded the first 59 on the European Tour at the same Dom Pedro Victoria Golf Course in 2018 and has again showed fine form this week.
Having come into the tournament at a lowly 112th in the Race to Dubai rankings, Fisher responded well under pressure with a six-under-par showing in the first round, and he replicated that score to head into day three at the top of the leaderboard at 12 under par.
A pinpoint 231-yard long iron on the par-five 17th, setting up an eagle, was a highlight of his performance.
Fisher said: "The thing with golf is anything can happen, just as I proved last year. I'm on the same score as I was at this stage last year in this tournament. I shot 71-59 and this year I’ve shot two 65s."
He added, according to the European Tour website: "I'm pleased to hit 65, I’m looking forward to the weekend."
South African Justin Walters and South Korean Wang Jeung-hun sat in a tie for second on 11 under, one ahead of Brandon Stone, also of South Africa.
Eddie Pepperell, who has finished third and second at this event in the previous two years, had a fruitful day, carding 66 to share fifth place overnight with South African duo Darren Fichardt and Haydn Porteous.
Overnight leader Louis de Jager was among seven players tied for ninth after he carded a disappointing 72, nine shots worse than his first-round total.