Golf: Lowest ever halfway total puts Rory McIlroy in full control

The 22-year-old Northern Irishman stands 11 under par after adding a 66 to his opening 65.

McIlroy even reached an unprecedented 13 under - and an amazing 10-shot advantage at the time - when he holed from 12 feet at the 17th.

But, needing a closing par four to become the first player to break 130 for two rounds at any of the majors, he went from rough to water and ran up a double bogey.

Yang then shot 69 to narrow the gap still further from eight to six.

McIlroy remains bang on course, though, to follow compatriot Graeme McDowell as champion and become the US Open's youngest winner since amateur Bobby Jones in 1923.

The world number eight refused to let his last-hole six take the shine off what until then had been another marvellous performance.

There was so much to admire, including a holed approach to the eighth for an eagle two that drew applause from playing partner Phil Mickelson.

"I'm feeling good - feeling very good," he said.

"It's funny to me. It feels quite simple. I'm hitting fairways, I'm hitting greens, I'm holing my fair share of putts. It's been two very, very good days of golf. I've put myself in a great position going into the weekend.

"But I know more than probably anyone else what can happen, so I've got to stay really focused and try and finish this thing off."

At The Masters in April, of course, he was four ahead with only 18 holes to go, shot 80 and lost by 10.

Winning golf's very next major after that experience would be the stuff of dreams, and that is what it is all about - not 36-hole records or matching the six-stroke advantage Tiger Woods held at Pebble Beach in 2000.

"These records, they're nice, but they don't really mean anything until the end of the tournament," he added. "If I can look back on this tournament with a trophy in my hand and look back at the records that would be nice."

Resuming three clear, he made a 25-footer at the fourth and pitched over water to six feet for another birdie on the long sixth.

The unexpected eagle two, courtesy of spinning a 113-yard wedge into the cup, enabled him to turn in 32 and then came further birdies at the 14th from four feet, long 16th - he actually missed a 10-foot eagle chance there - and 17th.

But then came a hook into the rough down the last and a second that curled into the water on the left. He had not had a bogey all week until then.

McIlroy stated: "It's been very near the best I can play. The second on the eighth was a bonus, but I hit a couple of iron shots on the back nine that were so pure.

"I'm halfway there, but there's still a long way to go.It's a big challenge, but every time I put myself in position I am becoming more and more comfortable and that's important."

Yang's 69 for five under prevented McIlroy from having a nine-shot 36-hole lead that would have equalled the biggest in all majors, a mark that has stood since 1934.

Spain's Sergio Garcia is part of the group on two under and five-time runner-up Mickelson would have been alongside them if he had birdied the last, but he also found water on the 18th and double-bogeyed for a 69 and one-over total.

England's Robert Rock remained one under after a 71. Padraig Harrington and defending champion McDowell were both two over after rounds of 73 and 74 respectively, while Lee Westwood had improved from four over overnight to one over with one to play.

Playing partner and world number one Luke Donald stood three over, just a stroke inside a halfway cut mark that was going to claim Martin Laird and the Lothians' Stephen Gallacher.

Play was suspended again just after 8pm, but Donald could feel safe that he had made it - and Laird and Gallacher were resigned to missing out by one regardless of what happened when the round was completed in the morning.