AUGUSTA, Ga. — When he was scolded by the woman who lives next door to the house he is renting in Augusta on Wednesday night for being too loud playing football with some buddies in the street, Rory McIlroy represented your average 21-year-old.

When he posted a 7-under-par 65 yesterday at Augusta National to become the youngest opening-round leader in the 75-year history of the Masters, McIlroy looked a lot more experienced than your average 21-year-old. He is tied for the lead with Spaniard Alvaro Quiros.

And when he spoke to reporters after the round about how much he learned from being in a similar situation in the British Open at St. Andrews nine months ago, McIlroy sounded much wiser than your average 21-year-old.

Indeed, McIlroy, despite his youth, has seen this movie before — but he plans on changing the ending.

At St. Andrews, McIlroy shot an opening-round 63 to take the early lead only to follow it with a windswept 80 in the second round.

“Because of the experience I have to draw from, being in a similar position, I feel better prepared to go out [today] with the lead,” McIlroy said. “At the time it was very disappointing to have that round, but it was probably very valuable in my progression as a golfer to have that to learn from.”

McIlroy said his experience at St. Andrews “will be a massive help” to him as he enters the second round.

McIlroy and Quiros hold a two-shot lead over K.J. Choi and Y.E. Yang, the 2009 PGA Championship winner, and a three-shot edge on Matt Kuchar and Ricky Barnes. Defending champion Phil Mickelson shot 70 and Tiger Woods shot 71.

“I’ll be thinking about it, and I’ll be thinking about how I can do things better [today] than I did that day in St. Andrews,” McIlroy said.

McIlroy is no stranger to being in contention at major championships, though he still is seeking his first win. He finished third in three of the past five majors.

His round yesterday was virtually flawless: He had seven birdies and no bogeys.

When he saw his pairing for the opening two rounds — he played with fellow youngsters Rickie Fowler and Jason Day — McIlroy’s spirits were immediately buoyed.

“I knew it was going to be a good group for us,” he said “It’s their first Masters and it’s my third, but we are all a similar age. It’s great that the draw came out like that.”

Said Fowler: “It looked like he was doing everything right.”

Asked about the “next generation” of players trying to break through and win a first major, Day said, “Rory is certainly very close.”

This is just McIlroy’s ninth major championship. He also played in the Ryder Cup last fall.

“I’m still relatively inexperienced, but I feel as if I’m a pretty quick learner,” he said. “I’m getting there. I mean, there’s no substitute for experience, especially in major championships, and I still feel as if I have a lot of learning to do.”

McIlroy is learning many things on the fly — like how to throw a football. He is a huge soccer fan, but living in Florida he now has taken to American football . That’s why he and his friends went to the mall Wednesday to buy the football that led to a scolding from their neighbor.

“Yeah, I was actually told off by the lady living across the street — we were making a bit too much noise,” McIlroy said. “We had to cut it short.”

Asked if he can throw a spiral yet, McIlroy said, “Yeah, it’s the thumb down, isn’t it? I’m learning.”

mcannizzaro@nypost.com