"We had the tougher side of the draw definitely – the most wind yesterday afternoon and we had some rain this morning."
Rare are the courses where an even par round will vault you up the leaderboard, but the weather coupled with the grueling course leaves Fox well aware of what is required to jump up near the top 10.
"It's definitely not enjoyable out there to play, it's just a grind. You know going out that if you make 18 pars you're going to make a lot of shots on the field.
"If you miss a green or you miss a fairway you pretty much hope you get lucky or miss it in the right spot and get a good lie because that rough's just brutal. I've managed to do that pretty well the last couple of days – the putter's been a little bit cold, if I had been able to hole a few I could have been three or four shots better but certainly not complaining."
Johnson is the overwhelming favourite to win the title, with the world number one holding a four shot lead over Scott Piercy and Charley Hoffman. In the history of the US Open, only six players have led by four or more shots after 36 holes. All bar one - Tom McNamara in 1909 - went on to raise the trophy.
"You've got to play really good golf if you want to shoot a good score, and I like where par is a good score on every hole, no matter what club you've got in your hand, what hole it is," Johnson said.
"I want to make things as easy as possible, even though they don't get any easier."
However, if he falters, there are some talented players waiting to pounce. Henrik Stenson, Justin Rose and defending champion Brooks Koepka are in a share of fourth at one-over, with Rickie Fowler a shot further back.
And, if things go to plan, Fox could find himself trending upwards as well.
'I've got a chance over the weekend. I might have to do something silly if Dustin keeps playing the way he is, but it's certainly nice to have some weekend golf."