Iain Carter and Jay Townsend have been chatting about the challenging course on BBC Radio 5 live sports extra.

Jay: "I think it's very refreshing to see the players challenged in a different way than they are normally."

Iain: "If you make it look too difficult you're going to put people off."

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Spencer Levin seems like he has fallen out of love with golf at the moment. The American, starting his second round at the tenth after a round of three over, began round two with three birdies in his opening nine holes.

But then things went wrong. He has since dropped five shots in his last seven holes, and one poor shot saw him hacking his club at the rough as he let his frustration boil over, before slamming his club repeatedly at the ground.

At least he only has two holes left today, and he is on four over overall, but will feel like it has been a wasted opportunity. Probably best staying out of his way for a bit.

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I questioned Dustin Johnson's putting ability, and he responds by claiming a birdie two at the sixth to regain a share of the lead.

His putt from 12 feet starts off left and swings back in line at just the right moment and vanishes into the middle of the hole. That is now four under once again for Johnson.

An overnight lead is in sight for the American, who has three holes left to play today.

Iain Carter
BBC golf correspondent at Oakmont Country Club

"When I chatted to Lee Slattery at the start of the week, he said playing well here against the best players would do wonders for his career."

A 72 opening round, followed by a 68 in round two for England's Lee Slattery. He is level par, currently tied 13th and will sleep well tonight.

Three under and in second place for the tournament, Dustin Johnson will certainly be satisfied with his work today.

However, he has come so close to picking up more shots on numerous occasions. His latest miss comes on the fifth, coming up just short from distance.

A bit more accuracy with the putter and he could well have had a sizeable lead tonight.

Thanks Pete. One final push everyone. It is nearly 8pm local time and the group consisting of Jason Day, Louis Oosthuizen and Adam Scott have seven more holes to play. Will they be able to finish today? The organisers certainly hope so.

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Here's how it stands at the top:

-4: Andrew Landry 

-3: Dustin Johnson (13*), Lee Westwood, Scott Piercy (16*), 

-2: Andy Sullivan (14*), Shane Lowry

-1: Sergio Garcia (13*), Daniel Summerhays (F),  Scottie Scheffler (a), Bubba Watson, Kevin Streelman, Danny Lee,

That seems like a good place for me to bow out for the evening. A report on the second round needs writing and will be live as soon as play ends for the day. Here's Michael Emons to see you through to the end...

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Daniel Summerhays is beaming as he records the low round of the week so far. A par at the last sees him post a five-under 65 to get to one under for the tournament. 

He's our clubhouse leader after two rounds, although Scott Piercy and Dustin Johnson will be mighty miffed if they don't eclipse him in the next hour or so.

Andy Sullivan a touch timid with another birdie attempt from 18 feet and he's staying at two under.

Things don't get any better on the next as the Englishman finds a greenside bunker on the par-three sixth.

Scott Piercy back to tied second on three under with a birdie on the seventh. Just two left to play for the American today.

Jason Day also in for birdie on the second to go to five over.

Danny Willett, currently nine shots behind the lead, took control of BBQ duties tonight with Lee Westwood and his agent Chubby Chandler.

Sergio Garcia's ball has a look at the hole before coming to rest a revolution away. A solid five though and one that will feel even better given his tee shot.

Dustin Johnson misses his birdie putt so that's a second three-putt of the week and a par five for the man in joint second on three under.

Over on the 11th Phil Mickelson sees a 33-foot birdie putt wander aimlessly by. Justin Day fires at the pin on the second. Big birdie chance to get back to five over.

Dustin Johnson trying to make the most of the benign weather. His second to the monster par-five fourth finds the front of the green but he is looking at a 100-foot putt for eagle. 

Sergio Garcia visited the rough from the tee and is playing his third shot from slightly further away, about 150 yards further away to be a little more precise. A decent eight-iron though and he has a 28-footer for birdie.

Johnson gives it a rattle and it's not going anywhere near the hole but that's a good effort and he's left with six feet for par.

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Andy Sullivan lags his birdie putt on the fourth to a couple of feet. I'm sure he would take pars on each of his remaining holes to reach the halfway point of the Championship on two under.

Scott Piercy on the short sixth, misses another short birdie putt and he stays two under with three to play.

Jason Day tries to work out his birdie putt on the first, sending it way right and watching as it curls round the back of the hole and four feet by.

There are birdies to be had out there. Daniel Summerhays has just rolled in his seventh of the round. He has had two bogeys but he's still five under for the round, one under overall with one to play

No wind and perfect conditions for those out there.

Iain Carter
BBC golf correspondent at Oakmont Country Club

"Speaking to the pros, the 12th and 13th holes here are two of the hardest holes in golf. Lee Westwood was sat watching the England match with me yesterday and just turned to his caddie and said: "Bill, Bill, how fast was that putt on the 12th." To which Billy Foster responded: "Lightning quick." 

Up ahead on the fourth, England's Andy Sullivan floats a wedge into a tight pin position - you can check it out on the photo below...he comes up a fraction short but is on the short stuff and will have a 30-footer for birdie.

Here's Phil Mickelson in his familiar black t-shirt and shiny trousers on the 10th green. It's another five-footer for par but he passes the test. Lefty is back to six over. Not out of the running just yet but he could do with picking up a couple of birdies. Not that he's heading for the easiest stretch of holes...

Rory McIlroy is out on the driving range. The Northern Irishman is not going to be playing again tonight. He said he would be popping in to work on a few things this evening and true to his word he has. He tees off his second round at 13:39 BST on Saturday.

Out on the course, Dustin Johnson smashes a massive drive on the 619-yard par five fourth. His ball speed was 186mph a neat graphic informs us. That's the quickest of the day. It's not all about pace and distance though. Accuracy is key at Oakmont and thankfully for DJ, he finds the right edge.

Shane Lowry, who is currently two behind the lead, speaking on BBC Radio 5 live sports extra:

"Yeah it was a good start. I would say I’m more comfortable than confident. The fact I play over here more often. I know more people in the locker room and it makes things easier for me and makes me relaxed."