No one has ever gone 13 under par in the U.S. Open ... until today, when Rory McIlroy birdied both the 16th and 17th holes at Congressional Country Club, in Bethesda, Md., to reach that mark. It's the lowest score achieved at any point in play in the tournament's 111 years.

Then, on the 18th hole, McIlroy double-bogeyed. McIlroy is still in excellent position. He finished 36 holes at 11 under par, another record, and McIlroy is sitting pretty with two more days of golf to go.

But fans are remembering his performance at the Masters, when McIlroy took a four-stroke lead into the final round, only to melt down and end up tied for 15th place, as the traditional green jacket went on Charl Schwartzel.

McIlroy is 22 years old. People at that age can feel foolishly invincible, or they can suffer nerves that a more mature player could control. Or they experience both states of mind in the same year, the same tournament, even the same round of golf.

But with a 10 stroke lead, McIlroy has a bit of a cushion, should he feel hands around his throat in the next two rounds.