While Lowry’s swing is flowing like fine wine and his driver a major offensive weapon, four time major winner McIlroy confessed that his swing is in such disarray that he faces a race against time just to survive the cut.

“There are scores out there to be had but you really need to be in control of your golf swing and today, or over the last two days, I haven’t been,” said McIlroy, who is 11 strokes behind co-leaders Dustin Johnson and Andrew Landry.

“There are low scores out there and if I’m able to get myself together, I feel like I will be able to shoot one of those and I can stick around for the weekend at least.

“I need to shoot something like 66 in the next round to give myself any chance.”

PGA Tour rookie Landry, 28, opened with a 66 to set the pace at four under par but must now go out to play his second at a quickly drying Oakmont this morning.

Johnson, on the other hand, added an impressive 69 to his opening 67 to match Landry’s four under total with 36 holes completed and can sit back and relax until late this afternoon before he has to go out for his third round.

Denied the title last year when he had two putts to win on the 72nd green at Chambers Bay but three putted, losing out to Jordan Spieth, 31-year Johnson has made just one bogey in an incredible ball-striking performance over the first two rounds.

He played 36 holes on Friday as officials bid to make up the time lost by Thursday’s rain delays and early suspension And at one stage he hit 25 consecutive greens in regulation.

“It was a long day today, but I felt like I played really solid all day for all 36 holes,” Johnson said. “I drove it really well. Hit a lot of great iron shots. Felt like I rolled the putter really nicely too. So very pleased with how it went today.”

Lee Westwood, who has also played just one round, lies solo third on three under after his 67 with Sergio Garcia tied for fourth with Lowry on two under after he holed a 50 footer for par on the ninth to add a 70 to his opening 68.

Scoring was tough late on Friday through there was a smattering of excellent scores with Daniel Summerhays adding a five under 65 to his 75 to move up to tied seventh with Andy Sullivan (71-68), one ahead of England’s Lee Slattery, added a 68 to his 72.

Lowry resumes at 8.50am local time today hoping to continue where he left off on Friday, when he completed his opening round by playing his last seven holes in two under par.

A beaming Lowry said: “Any time you shoot 68 around this golf course is a good day. I’m really happy the way I went out this morning. I holed some nice putts, some key putts coming in.

“I was more aggressive today and you have to hit driver. When you hit a good tee shot you can be more aggressive into greens and it will stop.”

McDowell’s 72 left him six off the pace as he went to lunch but while he ended the day seven behind Johnson and Landry, he was upbeat about his chances after closing with two birdies in his last four holes late last night for a second round 71.

Five over for the tournament and thinking about today’s cut line for the top 60 and ties with just five holes to go as he bogeyed the third and fourth (his 12th and 13th), he found his putting touch and holed a curling 15 footer for birdie at the par-three sixth and then scrambled for pars at the seventh and eighth.

The hooter sounded to warn players that play was suspended as he headed up the ninth, his 18th, he opted to finish in fading light at 8.42 pm and holed an unlikely 60 footer for birdie across one of the most treacherous greens on the course.

“It made up for some more ordinary putting earlier in the day,” McDowell said. “The greens were very difficult and very tricky this afternoon. They were certainly a foot to two feet quicker than they were in the morning and the pins were really treacherous.

“So I really feel like I hit good shots today. I hit it in some nice positions and the putter let me down a few times on my speed. I dropped a couple late coming in this morning and a couple got away from me late this afternoon as well. It was nice to finish well and make a big one on the last.

“I birdied the sixth and made a nice par save on seven, a nice par save on eight and a nice putt on the last so that made up for a weak day on the greens.”

With the course drying out rapidly, McDowell still believes he has a chance to win his second US Open if he can get back to around level par over the next two days.

“With the drying effect we are going to see this weekend, this golf course is going to get back to speed and level or a couple under par from here will have a sniff and it’s nice to be in the mix,” he said.

“It’s a funny feeling in the US Open. You look at the boards, especially this morning, and I was hanging in and hanging in and you look up expecting to see five under and no-one seems to do it.

“This golf course is so difficult, the way it is set up, the rough, the green complexes, it is a really tough test of golf. There are only a few guys who have separated themselves but they are not going to get far ahead. There is always a 75 out there if you get on the wrong side of these pins a couple of times.

“Level par is not going to be far away at the end of this week and three over through two rounds, I can legitimately get myself back to level over the weekend, continuing to play the way I am playing.

“I feel like I really close to my best form. My game is bubbling under the surface and I am going into this weekend with some good thoughts.

“I think I can compete but I obviously need a two or three under par round to get within touching distance. But I am going to need tough conditions on the weekend if I am to contend and level par is to win.”