Rory McIlroy played Muirfield Village once and wouldn’t miss it for anything.

They were the co-leaders going into the second round Friday, two players who have next to nothing in common. Riley played Thursday morning in the first group and went around so quickly — he already is among the fastest players in golf — that he didn’t have time to let too much thinking get in the way. Riley made eight birdies for a 6-under 66.

Then came McIlroy in the afternoon, plodding along until he hit his stride on the front nine. He not only made four birdies to catch Riley atop the leaderboard, the 22-year-old from Northern Ireland played so well that he missed three other birdie chances inside 8 feet.

Rory McIlroy made four birdies in the last eight holes to tie for the lead at the Memorial Tournament.

“A great way to start the tournament,” McIlroy said.

McIlroy only gets to play three regular PGA Tour events this year, and he showed why the Memorial is one of them.

“This is one of my favorite weeks of the year, one of my favorite courses,” McIlroy said. “I feel as if it really does set up well for me. I like these sort of golf courses, the likes of here and Akron (Firestone) and Quail Hollow. And I’m swinging well, I’m hitting it good and I’m holing a few putts. Hopefully, I can keep it going for the next three days.”

McIlroy likes to play the game through the air, the brand of golf most often seen in America.

But he doesn’t get out as often.

By giving up his PGA Tour membership last year, he is allowed to play only 10 tournaments. That includes the four majors and three World Golf Championships, with The Players Championship not counting against his number — although McIlroy chose not to play this year.

And that’s probably not going to change soon.

“Even if I did win, I still probably wouldn’t take my card up,” McIlroy said. “As a European and playing in some European events over the summer, like the French Open and the Irish Open, we have a very busy summer of golf. And I felt like after the PGA last year at Whistling Straits, I wanted to take a couple of weeks off just to refresh. You couldn’t really do it. You had a week off and then straight to the (FedEx Cup) playoffs. It was a lot of golf over a short period of time.”

Chris DiMarco and Josh Teater were at 67, followed by a large group at 68 that included Steve Stricker, Dustin Johnson, Stewart Cink and Rickie Fowler, the runner-up at the Memorial last year.

Fifty-one players in the 120-man field broke par.

Luke Donald, in his debut as the No. 1 player in the world ranking, recovered from a slow start by making four straight birdies toward the end of his round for a 70. He played with Masters champion Charl Schwartzel and four-time major champion Phil Mickelson, who each had a 72. Mickelson did that without making a single birdie on the par 5s.

This is the last tournament for McIlroy before the US Open, a chance for the No. 6 player in the world to atone for his 80 in the final round that cost him a chance to win the Masters. That collapse hasn’t stayed with him long. He was third the next week in Malaysia, and while he missed the cut while defending his title at Quail Hollow, he reached the quarterfinals of the World Match Play in Spain.

And now, the US Open beckons — along with a chance to win on another stronger course in America.

But first, a trip to Haiti.

McIlroy signed on as one of Ireland’s ambassadors to UNICEF, a partnership he takes so seriously that he is going on Monday and Tuesday to Haiti, which was ravaged last year by an earthquake.

“You want to associate yourself with a charity that you feel close to, and UNICEF works with mainly a children’s charity,” McIlroy said. “And I feel like I’m the sort of age that I can relate to younger people. I just don’t want to put my name on it. I wanted to do something, and they were very keen for me to go and see somewhere where they’re hands-on.

“It just fit in quite well that I could go to Haiti for a couple of days and see what they do.”