British golfer Rory McIlroy captured the first major of his career at this year's U.S. Open.

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Rory McIlroy heads the leaderboard at the Shanghai Masters after first round

McIlroy carded an opening round 68, one shot clear of Hunter Mahan in second

The winner at the Lake Malaren Golf Club is set to receive a check for $2 million

CNN  — 

World number three Rory McIlroy carded an opening round 64 on Thursday to finish eight-under-par and lead the Shanghai Masters by one shot.

The U.S. Open champion is in pole position to claim the $2 million winner’s check, a bigger prize than any of golf’s four majors, at the 30-man invitational tournament which is not affiliated with any of the sport’s professional tours.

McIlroy, 22, is one shot clear of American Hunter Mahan after a bogey-free round at the Lake Malaren Golf Club which included five birdies on the back nine.

“Very happy with my opening 64 at the Shanghai Masters…. Hopefully I can keep it going over the next few days!” McIlroy said via his official account on the social-networking site Twitter.

McIlroy was paired with fellow Briton Lee Westwood, just six days after McIlroy left former professional Andrew “Chubby” Chandler – the golf agent who also represents world No.2 Westwood.

Westwood, who along with Masters winner Charl Schwartzel and British Open champion Darren Clarke is still represented by Chandler, is tied for fifth after carding an opening round 69.

Three-time major champion Padraig Harrington and British duo Ian Poulter and Paul Casey share third on five-under, with the trio hoping to claim a large portion of the $5m prize fund.

China’s Li Chao made a strong start, shooting 68 to sit level with American Anthony Kim on four-under.

Level with Westwood on three-under is stablemate Schwartzel, two-time major champion John Daly, double U.S. Open winner Retief Goosen, 2010 British Open champion Louis Oosthuizen, Sweden’s Robert Karlsson and South Korean Y.E. Yang.