Rory McIlroy believes Martin Kaymer needs just two level-par rounds to win the US Open, but feels his Ryder Cup team-mate should keep his foot flat to the floor at Pinehurst.
Kaymer carded a second consecutive 65 on Friday to post a 10-under-par total of 130, equalling the lowest halfway score in major championship history and eclipsing the US Open record of 131 set by McIlroy himself at Congressional in 2011.
That gave the German a six-shot lead over American Brendon Todd, with McIlroy another three shots back after a second round of 68.
"If I was Martin, hopefully I would be thinking about how to get seven ahead and then how to get eight ahead and then how to get nine ahead," said McIlroy, who went on to win by eight shots at Congressional with a tournament record total of 16 under.
"Especially on a golf course like this, you can't go out trying to protect anything.
"You've just got to keep the foot to the floor and just keep it going. If he's comfortable out here and making birdies, then that's what you should still be thinking of.
"Ten under par is an incredible total after 36 holes and, if he can hold on to that 10-under total, he's going to win this tournament.
"I learned at the Masters, the previous major before Congressional, if you get too defensive, it's detrimental."
That was a reference to McIlroy taking a four-shot lead into the final round at Augusta in 2011 before slumping to a closing 80.
Speaking about his chances of a second US Open title this weekend, the 25-year-old added: "If I have a couple more 68s, I would take my chances. With a five-under total I would sit in the clubhouse happily with that.
"If someone had told me at the start of the week that I was going to be standing here one under par after 36 holes, I would have taken it.
"I would have said, 'perfect, let me play the weekend and see what happens'.
But what Martin has done over the first couple of days has made one under par look pretty average.
"But I'm happy with where my game is and there's a lot of golf left to play. So we'll see what happens over the weekend."