McIlroy and Riley take joint control at Memorial

Rory McIlroy of Northern Ireland watches his second shot on the 10th hole during a practice round for the Memorial Tournament at Muirfield Village Golf Club in Dublin, Ohio June 1, 2011.

DUBLIN, Ohio (Reuters) - Rory McIlroy birdied three of his last four holes at one of his favourite venues to surge into a share of the lead in Thursday's opening round at the Memorial tournament.

The mop-haired Northern Irishman fired a sparkling six-under-par 66 in ideal scoring conditions at Muirfield Village Golf Club to end the day level with American journeyman Chris Riley.

Chris DiMarco and Josh Teater each opened with 67s on a 'Stars and Stripes' leaderboard where McIlroy was the only non-American among the top-21 players.

"I'm really happy with the way I played today," McIlroy, 22, told reporters after a sizzling birdie-birdie-birdie-par finish to his round in glorious late afternoon sunshine.

"I got it up and down a few times when I really needed to, to keep myself at a couple under, and then was able to birdie a few holes coming in. That was really the difference.

"I feel comfortable, I'm swinging well, I'm hitting it good and I'm holing a few putts. Hopefully I can keep it going."

McIlroy, who tied for 10th last year on his Memorial debut, loved the undulating, heavily wooded layout the first time he played it.

"This is one of my favourite weeks of the year, one of my favourite golf courses," the world number six said. "I feel as if it really does set up well for me.

"I like these sorts of golf courses, the likes of here and Akron and Quail Hollow which are tree-lined," added McIlroy, who won his maiden PGA Tour title at last year's Quail Hollow Championship.

RAISED EYEBROWS

While the sight of McIlroy at the top of the leaderboard came as no surprise to anyone, the presence of Riley raised a few eyebrows.

The 37-year-old American had missed the cut in his three previous starts at Muirfield Village, never once breaking par.

"I really putted good," Riley said after totalling only 25 putts. "I made a lot of nice par saves.

"I made one on six, my 15th hole, from like 20 feet for par and on the first hole I made about a 15-footer for par. It was just one of those days where everything was going in the hole, and it felt pretty good to see that."

British world number one Luke Donald recovered from an opening nine of two-over 38 to card a six-birdie 70 while fourth-ranked American Phil Mickelson returned a 72.

Donald's low point came with a double-bogey at the par-four 18th, his ninth hole, where his approach ended up in a bunker and he needed two more shots to reach the green.

"I hit a great eight-iron right at the pin and it came up maybe two yards short of being perfect and kicked back in the middle of the trap," the Englishman said. "I just got a little bit too cute.

"I hit a poor bunker shot, another poor chip and lipped out the (bogey) putt. So taking four from literally 20 feet wasn't what I was hoping for."

Donald, who became world number one with a playoff victory over fellow Briton Lee Westwood in the European Tour's PGA Championship Sunday, was warmly greeted by the fans as he made his way round the course.

"A lot of people were saying congrats," he said. "I heard a few 'No. 1' shouts and stuff like that, so you feed off that."

World number eight Steve Stricker and U.S. Ryder Cup team mates Rickie Fowler, Stewart Cink and Dustin Johnson were among a group of nine players knotted at 68.

Britain's Justin Rose, who won last year's Memorial tournament by two shots, launched his title defence with an opening 71.

(Editing by Julian Linden)