Doug Mills/The New York Times  Rory McIlroy took a commanding lead on Friday at the Congressional Country Club. More Photos »  BETHESDA, Md. — Through 35 holes of the 111th United States Open, Rory McIlroy was in a zone of his own, scorching Congressional Country Club with birdies — almost at will — and strutting as close to perfection as any golfer has during this annual survival test.  But as McIlroy’s sports psychologist has no doubt told him, golf is not a game of perfect. McIlroy, the 22-year-old star from Northern Ireland — who had not bogeyed a hole in two days, had missed only three greens and almost no putts and had opened a chasm between himself and the rest of the field — spilled gravy on his tie at the end of the meal.  McIlroy double-bogeyed the lengthy 18th hole for a round of 66 and a total of 11-under-par 131. It meant that he broke the United States Open record for low 36-hole total by only one stroke instead of three, and he only tied Tiger Woods’s record for the largest 36-hole lead — six strokes — set in 2000 at Pebble Beach, where Woods won by 15 strokes.  McIlroy is not cluttering his mind with concerns about 36-hole records or protecting his six-stroke lead over Y. E. Yang (69) or his recent meltdowns in major championships. He is not worried that if he does not win this week, people will question whether he is made of stern enough stuff to close out a major.  That was the old McIlroy, the one who swooned in April when he led the Masters on the 10th tee on Sunday and shot a 43 coming in; the one who shot a 63 to lead the British Open last year before shooting an 80. He said he had changed his attitude and his on-course demeanor to reflect his confidence in his game.  “I did a piece after Augusta where I said, ‘I needed to be a little more cocky, a little more arrogant on the golf course, and think a little bit more about myself,’ ” McIlroy said. “Which I’ve tried to incorporate a little bit, just on the golf course.  “I just try and have a bit of an attitude, you know?”  It showed. With shoulders back and chest out, McIlroy took Congressional apart with a systematic barrage of iron shots that parachuted close to the holes and putts that ran in from everywhere on greens softened by overnight rains. He birdied the fourth and sixth holes and stunned the large crowds when he backed a wedge shot into the hole from 114 yards for an eagle at No. 8.  Yang said he was not worrying about catching McIlroy or shooting anything too low. He said he would just do what he does best, which is stalk the lead relentlessly.  “I’m not imagining this as a chase; it’s just about me playing another solid round tomorrow,” Yang said. “He could have another spectacular round, but I can’t react to that.”  McIlroy’s swing was so much on plane and his timing so languid, he looked like a teenager playing Wii golf on a big-screen television. His towering 6-iron from 190 yards at the 14th hole climbed to its apex and swooped into the green like an Everglades kite diving on a baitfish.  At the 16th hole, he hit a picturesque 4-iron that just cleared the collar and landed soft, staying 10 feet below the hole. That birdie putt moved him to 12 under par.  “Those iron shots were pure,” he said in the day’s biggest understatement.  At the 17th hole, he hit a 7-iron in from 175 yards and made the putt to go 13 under par, the lowest score anyone has reached in an Open.  While all this was going on, some fellow professionals were finishing their rounds feeling as if they had played a course entirely different from the one McIlroy was taking apart like a safecracker.  “He is playing great golf, simple as that,” Sergio García said after his 71 put him at two under par. “Even if what happened at Augusta would have not happened, it would be nice for him to win. I think he deserves it, and hopefully he’ll be able to do it.”  Padraig Harrington of Ireland, a three-time major championship winner, said: “He’s got enough experience, and I think he’s learned enough at this stage. This golf course suits him. It will only suit him even more on the weekend as they’ll toughen it up. It plays to a guy who has a lead.”  Graeme McDowell, the defending United States Open champion and a fellow Ulsterman, said McIlroy had paid his dues and was ready to win his first major.
In the second round on Friday, Rory McIlroy reached an astonishing 13 under par, finishing at 11 under.