Mikko Korhonen produced another flawless performance at Diamond Country Club to put himself firmly in control heading into the final day of the Shot Clock Masters.
On a day when the first ever bad-time penalties were handed out on the European Tour, the Finn stayed bogey-free through 54 holes with a 68 that moved him to 13 under and handed him a five-shot lead over South African Justin Walters.
The innovative format this week is the first time every player has been on the clock for every shot and Korhonen will hope the firsts do not end there as he goes in search of a maiden victory in his 146th European Tour appearance.
Korhonen has earned his stripes the hard way, going to the Qualifying School 12 times, winning the Final Stage in 2014 and keeping his card ever since.
The 37 year old was runner-up here last season and will take the biggest 54-hole lead of the season into Sunday.
“I'm very excited, it's the first time I've been in this position so I'm looking forward to it,” he said.
“I guess I'm just hitting fairways, hitting greens, making a few putts. That's all really. I've felt good swinging and also putting. I have the pace pretty good on the greens.
“I have a game plan which I'm going to follow. I'm not going to say anything more about it. I've been doing that for the past three days and I'll keep doing it.”
Walters missed a host of birdie chances in a level par 72 to sit a shot ahead of Australian Adam Bland, Canadian Austin Connelly, Swede Peter Hanson, England's David Horsey, Dane Jeppe Pape Huldahl, Spaniard Miguel Ángel Jiménez, Scot Connor Syme and 2016 champion Wu Ashun.
After no bad-time penalties were handed out on days one and two, Austrian Clemens Prader took four seconds over his allotted 50 to take a putt on the 16th, becoming the first man ever to be handed a bad-time penalty.
Scot Grant Forrest and Italian Andrea Pavan later joined him as players to be docked a shot after running out of time.
Korhonen extended his overnight lead to two shots with a birdie on the par five first thanks to an approach to four feet and a ten-footer on the third moved him further ahead.
Walters bogeyed the third but he would then make 12 pars in a row as Huldahl emerged as the closest challenger with birdies on the second, sixth and ninth to get to ten under and cut the lead to one.
An approach to eight feet on the ninth moved Korhonen back to two ahead and when he holed a long putt with a vicious right-to-left break on the tenth, he was three ahead.
Bogeys from Huldahl on the 11th and 13th extended the lead to five and Walters joined him in second as he took advantage of the par five 16th, with Huldahl dropping another shot on the last.
Bland equalled the lowest round of the day with a 66 containing birdies on the first, third, fourth, sixth, tenth and 11th, while Horsey had a single bogey in a round of 68.
Hanson was on the charge as he birdied the first, fifth and sixth but could not make further progress, and Connelly also signed for a 69 containing seven birdies.
A chip-in on the 13th was the highlight of Syme's 69, with Jiménez and Wu matching Huldahl with rounds of 72.
England's Lee Slattery matched Bland's 66 to sit at six under alongside Swedish pair Oscar Lengden and Oscar Stark, home favourite Matthias Schwab, Australian Nick Cullen and Frenchman Raphaël Jacquelin.