Starting at the back nine, the Englishman birdied the 18th and was on course for a 2-under 70 before his late slip at the ninth sent him tumbling down the leaderboard at the $2.8 million tournament at the Blackstone Golf Club at Icheon. He finished at par 72.

Westwood, who won the Asian Tour's Indonesian Masters last week to regain the No. 1 world ranking, appeared distracted by spectators taking photographs. Twice in the last three holes he backed off shots due to clicking noises, dropping three shots in the process.

Despite the poor finish, Westwood was satisfied with his performance. "I'm still in contention," he said. "On the first 15 holes I played very nicely and gave myself a lot of chances without really making any putts." Ian Poulter and Ernie Els also had inconsistent rounds.

Poulter started with consecutive double bogeys before bouncing back to post a 2-over 74. The Englishman later said that he can perform better and "get birdies on this course." South African Els, winner of three majors, shot a 73.

South Korea's Y.E. Yang, the first Asian to win a major, also struggled and posted a 4-over 76.

McGrane, who has a good record in Asia with his only previous tour victory at the 2008 China Open, birdied two of his final four holes to post a 6-under 66.

"I made plenty of birdies and I was very satisfied with that and I putted well today and I had good pace on my putts which is important to me," the Irishman said.

McGrane was a shot ahead of South Korea's Park Sang-hyun, Richard Finch of England and Felipe Aguilar of Chile, who all posted 5-under 67s.

The tournament is co-sanctioned by the Asian tour, the European tour and the Korea PGA.