After weather delays on the opening two days, the second round was completed yesterday morning at Blackstone Golf Club, with Thailand's Kiradech Aphibarnrat completing a superb round of 66 to join compatriot Arnond Vongvanij and Australian Wade Ormsby at the top of the leaderboard.
Oosthuizen was three shots back after rounds of 69 and 71, but the world No.7 - who made the journey from Florida to South Korea in a private jet laid on by the tournament sponsors - picked up three birdies in his first five holes. At seven under par he joined a seven-way tie for the lead, with a total of 34 players within four shots of the top spot.
Aphibarnrat, winner of the Malaysian Open last month, briefly led on his own after recovering from a poor drive on the par-five first to make a birdie, only to bogey the second. Ormsby, who won his first professional event on the Asian Tour in India earlier this month, opened with three straight pars, while Vongvanij dropped back to six under after a bogey on the second.
Korea's Heung-chol Joo, the world No.916, was giving the home fans plenty to cheer about, recovering from a bogey on the first with four birdies in a row from the third to join the leaders on seven under.