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Rory McIlroy put up a dazzling score on the opening day of the British Open.

Yawn.

Let's see if he can do it again.

McIlroy heads into Day 2 at Royal Liverpool with a one-shot lead after a 6-under 66, a familiar position that either sets him up for a good run at the claret jug — or another dose of second-round failure.

This year, McIlroy has started a couple of tournaments with 63s and another with a 64, but wasn't able to win any of them. For some reason, he's had a serious case of the yips in the second round, putting up a cumulative score of 15-over par compared with 55 under for the opening round, and 39 under on the weekend.

Talk about Freaky Friday.

"It's not like I've shot good scores in first rounds and haven't backed them up before," McIlroy said. "I'm used to doing that. I just haven't done it recently.

"Hopefully," he added, "it's just one of those things and I'm able to turn it around."

As with any British Open, the weather will likely play a major role.

On Thursday, McIlroy and the other morning starters benefited from pristine conditions — sunny and mild, with only a hint of a breeze off the Irish Sea. But heavy rain was in the forecast for Friday, which could make things a lot more interesting.

"We had perfect scoring conditions," said McIlroy, who didn't make a bogey and birdied three of the four par-5s. "There were plenty of opportunities to make birdies. I was able to take a few of them. Another great start and looking forward to getting back out there."

He'll have plenty of competition.

Seventeen players were within three shots of the lead, including Tiger Woods. In his first major of the year, the 14-time champion bounced back from bogeys at the first two holes to shoot 69.

The world's top-ranked player, Adam Scott, also got off to a strong start with a 68.

Here are five other things to look for in the second round of the British Open:

TIGER'S BACK: In only his second tournament since undergoing back surgery on March 31, Woods rolled in a 30-foot putt from the fringe at No. 11 to spark a run of five birdies in six holes. He looked like the Tiger who romped to victory the last time the Open was held at Royal Liverpool in 2006. It remains to be seen if Woods, with so little playing time this year, can hold it together over four rounds. He hasn't won a major since the 2008 U.S. Open, the longest drought of his career and making it increasingly unlikely he'll catch Jack Nicklaus' record of 18 championships.

BROTHERS IN ARMS: Edoardo and Francesco Molinari know about togetherness. The brothers teamed up to win the World Cup for Italy in 2009, and they were partners for Europe's winning Ryder Cup side the following year. Now they are together on the British Open leaderboard. About 30 minutes after Edoardo signed for a 68 in the opening round, Francesco rolled in a 15-feet eagle putt at No. 18 for the same score.

YOUTH MOVEMENT: The last three Open champions have been in the 40s. But the kids were all right on Day 1, with 25-year-old McIlroy setting the pace and 21-year-old Matteo Manassero one stroke back with a 67. Right on their heels were 22-year-old Hideki Matsuyama (69), 24-year-old Brooks Koepka (68) and 25-year-old Rickie Fowler (69). "I hope someone in their 20s wins," Koepka said. "I hope it's me."

LEFTY'S LAMENT: Phil Mickelson hasn't won since his victory at last year's British Open, and Lefty showed no signs of breaking out of his slump by starting with a 74 at Hoylake. The 18th hole summed up his frustration — he knocked his second shot out of bounds and had to take a cart all the way back to the spot where he struck the ball for a do-over. He wound up making bogey at the par-5 hole, one of the easiest on the course.

ENGLISH MISERY: The home country had high hopes of producing the first English champion at an Open being held in England since Tony Jacklin at Royal Lytham in 1969. Those took a big hit on Thursday, when the best score by a local was amateur Ashley Chesters with a 70. Lee Westwood (71) was the only other English player to break par, while Justin Rose settled for a 72, Luke Donald and Ian Poulter shot 73, and Paul Casey struggled to a 74.

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