Shane Lowry takes the rough with the smooth

You want integrity in sport? You got it from Shane Lowry. After self-assessing a one stroke penalty on the 16th green - his seventh - when his ball moved ever-so-slightly on address, the 29-year-old Offalyman kept his composure to shoot a second round 70 for 138, two-under-par, that put him into tied-third behind midway leader Dustin Johnson in the US Open at Oakmont Country Club, outside Pittsburgh.

If there once was a time when the head gasket might have blown after such an infraction, Lowry remained cool, calm and collected as temperatures hit the mid-89s Fahrenheit and there was some redemption for him as he fashioned a par-save with a putt down the slippery slope on his finishing hole.

But it proved to be a disastrous run home for Rory McIlroy, playing in the group ahead of Lowry. The world number three - who had opened with a 77 - started off like a train in playing catch-up and covered the front nine in just 29 strokes as he leapfrogged through the field and seemed set to move from the fringes into contention.

However, a four-putt double-bogey from 12 feet on the third, his 12th, cost him dearly and McIlroy bogeyed the eighth, his penultimate hole, and then ran up a double-bogey six on his finishing hole where he took two shots to escape a fairway bunker. McIlroy - 71 for 148, eight-over - was in no mood to talk afterwards.

Lowry suffered a bogey on the 10th, his opening hole, and suffered another bogey on the 16th where, after hitting his tee shot to 30 feet, the ball moved as he addressed the putt. “I hit a nice 6 iron into the right-hand side of the green and had a straightforward two putt from 30 feet up the hill. I addressed the ball, and the ball moved back. I had to penalise myself. It’s very frustrating in a tournament like that,” he remarked.

After calling over the referee and informing him that the ball had moved and he was assessing himself a penalty stroke, Lowry then rushed his next putt and was left with an eight-footer for par which he sank. “If I would have missed that, it would have been difficult to get back from there. That kind of kept me going, and from there on, I just played good golf. In fact, I played good golf all day, didn’t hit it in trouble very much. Hit plenty of fairways, plenty of greens, and that’s what you need to do out here,” said Lowry.

He added: “To hole that second putt was massive for me and massive for my whole day. Because I miss that, and all of a sudden I’m over par for the tournament . . . when you get over par, you start to think, where can I pick up a birdie? And you might start forcing it. So that was big for me.”

Lowry collected his first birdie of the day on the Par 5 fourth - holing from 15 feet - and rolled in an eight footer on the Par 3 sixth to get back to level par on his round and then showed his deft short game off to great effect with up and downs for pars on the eighth and ninth.

The par on the ninth was out of the top drawer: after finding a fairway bunker, he laid up and hit a wedge approach some 20 feet above the hole. With the greens running at 14 on the stimpmeter, he rolled the putt into the centre of the hole to sign for a 70 that put him two strokes behind Johnson going into the delayed third round.

“I’m very happy with the way I hit the ball. My putter feels good in my hands as well. I’m happy with the way my game is going into (the third round),” said Lowry.

Johnson held a one stroke lead over Texan Andrew Landry going into the third round, with Lowry in four-way share of third with Sergio Garcia, Gregory Bourdy and Scott Piercy. Graeme McDowell - who finished his second round with a 71 for 143 on Friday night - was in tied-27th.

The cut fell on six-over par 146, with 67 players surviving into the final two rounds. McIlroy, Phil Mickleson, Rickie Fowler, Justin Rose and Patrick Reed were among those who missed the cut.