Paul Dunne fired a brilliant bogey-free 64 to set the clubhouse target on day one of the Turkish Airlines Open.
The Rolex Series was in town at Regnum Carya Golf & Spa Resort and Irishman Dunne was keeping a world-class field at bay at seven under in Antalya.
Countryman Padraig Harrington and China's Li Haotong were at six under in the closing stages of their rounds, with another Chinese in Wu Ashun and Belgian Thomas Detry in the clubhouse two shots off the lead.
There was then a large group at four under including defending champion Justin Rose and fellow Major Champions Martin Kaymer and Danny Willett.
Harrington began his round with three birdies and Dunne had gains on the 11th, 13th and 15th to join the early group at the top.
A four-foot putt on the fifth handed Harrington the lead but Dunne joined him with a birdie on the 18th before trouble off the tee on the seventh led to a first bogey of the day for Harrington.
A second consecutive gain on the first handed Dunne a two-shot advantage but a stunning approach to the ninth put Harrington within one.
The three-time Major Champion holed a six-footer at the par five 12th to get into a share and when he followed it with another gain on the next, he was one clear of Dunne.
The 2017 British Masters champion would not be denied, however, and he holed an eight-footer on the seventh before rolling in a long right-to-lefter on the tenth to set the target.
Harrington had two holes left of his round to play, while Li had completed 15 holes.
The two-time European Tour winner started birdie-bogey and added further gains on the third, fourth and ninth to turn in 31 before he chipped in to save par on the tenth. Another chip-in on the 12th brought an eagle and he then capitalised on the par five 15th.
Detry was bogey-free with gains on the 12th, 13th, first, fourth and ninth, while Wu had a single bogey on the tenth to go with birdies on the fifth, sixth, seventh, 11th, 14th and 15th.
Malaysian Gavin Green, England's Chris Paisley and South African Erik van Rooyen were in the clubhouse at four under, with Kaymer, Rose, Willett, Kiradech Ahpibarnrat, Sam Horsfield, Thorbjørn Olesen, Tapio Pulkkanen, Julian Suri and Lee Westwood all on the back nine.