Last Updated: 14/06/14 2:18pm
McIlroy: Won the US Open in 2011 having recorded a total of 131 over his first two rounds
Rory McIlroy believes Martin Kaymer should look to press home his sizeable advantage as the German looks to claim victory in the US Open.
Kaymer carded a second successive round of 65 on Friday to post a 10-under-par total of 130, thus equalling the lowest halfway score in major championship history.
This also gave the 29-year-old a six-shot lead over American Brendon Todd in the 2014 tournament.
McIlroy, who held the previous halfway record at the US Open courtesy of the 131 he scored in 2011 en route to winning the event at Congressional, is three shots back after a second round of 68.
The Northern Irishman believes two level-par rounds will probably be enough for Kaymer to win his second major but does not think his Ryder Cup team-mate will let up.
"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.
"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."
"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 own chances of success this weekend, McIlroy 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."