The South Korean youngster Noh Seung-yul overcame an injured ankle to hit a bogey-free round of 63 to trail US Open champion Rory McIlroy by two strokes at the halfway stage of the $US 5 million Shanghai Masters golf tournament.
The 20-year-old Noh hit nine birdies to set a course record on the Lake Malaren course in Shanghai, designed by Jack Nicklaus, for a two day total of 135.
McIlroy struggled on the front nine, bogeying the fourth hole and then dropping two shots on the ninth but he recovered with four birdies on the back nine for a three-under 69.
American Anthony Kim and South Africa Louis Oosthuizen were three strokes behind the leader at joint third while Ireland's Padraig Harrington and American Hunter Mahan were a shot further behind at tied fifth.
Thirty players are fighting for the first prize of $US 2 million in the inaugural event, which is not sanctioned by a major tour and does not have world-ranking points.