Dublin, OH (SportsNetwork.com) - Rory McIlroy fired a 9-under 63 on Thursday to race into the early lead of the Memorial Tournament.
McIlroy is coming off his sixth career European Tour win at the BMW PGA Championship last week, but is seeking his first victory on the PGA Tour since the 2012 BMW Championship.
"I'm really happy and obviously a really good opening round," said McIlroy.
Masters winner Bubba Watson, Paul Casey and Chris Kirk carded matching 6-under 66s at Muirfield Village Golf Club to share second place, while Keegan Bradley, Michael Thompson and J.B. Holmes are tied for fifth at 5-under 67.
Hunter Mahan, Ryan Moore and Justin Leonard shared eighth at 4-under 68. Adam Scott, who also won last week at the Colonial, Jordan Spieth and Aaron Baddeley were among a group of 10 players to shoot a 3-under 69 and occupy 11th place.
McIlroy opened his impressive round with a par at the first before rolling in a 10-foot birdie at the second. After converting a 9-foot birdie effort at the fourth, he reeled off three birdies in a four-hole stretch from the seventh to race to 5-under.
He stayed hot with a 27-foot eagle putt at the 11th and converted a 15-foot birdie putt at the 13th to reach minus-8.
McIlroy then found some trouble at the par-4 14th, where he hit his second shot into a greenside bunker and needed two shots to escape.
His fourth rolled past the green and he chipped his next to within two feet. He kicked in that for a double-bogey 6.
But he quickly got those shots back when he found the green with his second shot at the par-5 15th and rolled in a 15-foot eagle to get back to 8-under. He moved to 9-under with a 13-foot birdie at the 16th and parred his final two holes to end there.
"I obviously played really well from tee to green. I holed a lot of putts as well, two really good up and downs at the last two holes," said McIlroy. "It could have been even better, apart from the double-bogey on 14."
Watson started on the back nine and recorded back-to-back short birdie putts at the 12th and 13th to reach 2-under.
A 6-foot eagle putt at the 15th moved him to minus-4, but he gave both of those shots back with consecutive bogeys at the 16th and 17th.
He would par the next five holes before catching fire with four birdies over his final five holes to end at 6-under.
"Today there was really no wind for the whole round. A little bit of rain yesterday softened it up, so conditions were favorable for good scores," said Watson. "It's still a tough golf course. It's not like they're just handing you birdies, but you still have to play some good golf, hit some quality shots."
Casey countered a pair of bogeys with an eagle and six birdies to also finish at minus-6, while Kirk had seven birdies and a bogey during his opening round to earn his share of second place.
NOTES: McIlroy's best finish at the Memorial was fifth place in 2011 ... McIlroy holds the first-round lead for the ninth time in his career ... Since the tournament started in 1976, only two first-round leaders/co-leaders have managed to go on to win; Ernie Els (2004) and Justin Rose (2010) ... Casey is playing on a sponsor's exemption ... Defending champion Matt Kuchar carded a 2-over 74 during his first round and sits in a tie for 87th place.