"It definitely wasn't as easy as it was the first couple of days," said McIlroy, who recorded championship lows for fairways hit (eight) and greens in regulation (14). "I knew that I was going to feel a little bit of pressure and a little bit of nerves, and it took me a few holes to get into the round."
At the 480-yard, par-4 third, McIlroy drove into the right rough and punched back into the fairway. From 99 yards on his approach, McIlroy threw the ball just beyond the flagstick and spun it back for a tap-in par.
"That gave me a little bit of momentum," said McIlroy, who has shot 69 or better in one-third of his 39 rounds in majors. "I sort of found my rhythm quite quickly after that."
He needed the outward nine to recoup the two strokes he lost with Friday's double bogey on the 18th hole. With a birdie at the 556-yard, par-5 ninth, McIlroy headed to the second nine with an eight-stroke lead.
On the inward nine, he bogeyed the 191-yard, par-3 10th--his first bogey of the championship--but got it back one hole later. A birdie at the 473-yard, par-4 14th made more history, and he parred in from there.
While the celebrating of a new champion—McIlroy would be the fifth straight first-time major winner—appears to be a formality, there remain a few players not quite ready to concede.
Y.E. Yang (1-under 70) is at 6-under 207. World No. 2 Lee Westwood and Jason Day shared the day's low round of 65 and are tied with Robert Garrigus (68) at 5-under 208. Fredrik Jacobson (66), Matt Kuchar (69) and Sergio Garcia (69) are at 4-under 209.
"I think it's actually a race for second place right now," said Yang, the 2009 PGA champion who caught and passed Tiger Woods in the final round at Hazeltine National Golf Club. "I'll try and catch up with Rory as much as possible. But if he doesn't let go, it's going to be a race for second place."
Fifty-one years ago at Cherry Hills Golf Club, Arnold Palmer took offense to Pittsburgh Press writer Bob Drum's contention that he had no chance of catching Ben Hogan in the final round.
Palmer promptly posted 65 and won his only U.S. Open. In doing so, he set the record for largest final-round comeback, seven strokes. Six years later at The Olympic Club, Palmer blew a seven-shot lead over the final nine holes and lost a Monday playoff to Billy Casper.
Westwood, who has four top-three finishes in the last six majors and seeks his own first major, bristles at the notion this is a done deal. He makes note of McIlroy's dalliances with 80 in two of the previous three majors.
"You don't know how Rory is going to do," Westwood said. "You don't know how he's going to deal with the big lead. He had a big lead in a major and didn't deal with it well before. There's pressure on him with regards to that. So we'll see."
What everyone has seen so far is McIlroy adding new chapters to the record book..
Saturday, McIlroy penned two records--the lowest 54-hole U.S. Open score (199), bettering Jim Furyk's 200 in 2003 and the lowest score in relation to par at any point (14 under).
And the McIlroy on display this week is a mentally tougher player than the one who held the 54-hole at the Masters two months ago.
"From the experience that I had at Augusta, I know now how to approach tomorrow, and I think that's the most important thing," McIlroy said. "At Augusta, it was all a little bit new to me, going into the final round with the lead. I didn't know whether to be defensive, aggressive, go for it, not go for it, but now I know what I need to do, which is a great thing to have. I have a clear mind going out there tomorrow, and I just need to stick to my game plan. "
Over the past two days plenty of players have sung McIlroy's praise, including Irishman Padraig Harrington who went as far as to suggest that it will be McIlroy, not the absent Tiger Woods, who will break Jack Nicklaus' record of 18 majors.
"Oh, Paddy, Paddy, Paddy," was McIlroy's response to that notion. "You know, I'm still looking for my first one. That's all I can say. I'm looking for my first one. I've put myself in a great position to do that tomorrow, and then we'll see what happens from there."