It was the defining moment for Rory McIlroy late Saturday afternoon at the Masters.

And it was loud enough to rattle Tiger Woods.

That birdie on the 17th hole — which caused Woods to back off his shot ahead of him on the 18th hole — sent the 21-year-old from Northern Ireland to a 2-under 70 and gave him a four-shot lead going into the final round.

It’s the largest 54-hole lead at the Masters since Woods led by eight strokes in 1997.

"It’s a great position to be in," McIlroy said. "I feel comfortable with my game, comfortable with the way I prepared, and all of a sudden I’m finally feeling comfortable on this golf course. With a combination like that, you’re going to feel pretty good."

He is making it look easy.

That bounce in his step turned into a swagger as he walked to the 18th tee, ripped another drive and walked up to the 18th green to a loud ovation that could be a preview to a coronation.

Following him around was U.S. Open champion Graeme McDowell, who missed the cut but didn’t want to miss out on his countryman having a chance to give Europe another major.

"He just texted me and told me he loves me," McIlroy said. "I don’t know if that’s him or the beer talking. No, it’s great to see him out there and I appreciate his support. He’s going to know how I’m feeling. Here’s a major champion and he got it done last year at Pebble. Hopefully, I can emulate that feeling and get a major myself."

McIlroy was at 12-under 204 and will play in the final group Sunday with Angel Cabrera, who won the Masters two years ago and is the only major champion within six shots of McIlroy.

Cabrera has fallen to No. 97 in the world, with only two top 10s in the last year. He didn’t think he had much of a chance when he arrived at Augusta. But he’s starting to believe.

"Now that I see that I’m playing well, I sure think I can do it," Cabrera said.

The group at 8-under 208 also includes Charl Schwartzel (68), K.J. Choi (71) and Jason Day, the 23-year-old Australian who took the lead on the front nine with a long birdie on No. 5, but paid for his aggressive putting and had to settle for a 72.

The challenge from Woods, who started the third round only three shots behind, never materialized.

He squandered birdie chances with a fairway metal that went too long on the par-5 eighth, a 5-foot birdie putt that never had a chance on No. 9, a shocking miss for par from 2 feet on No. 11 and a three-putt par on the 15th after an amazing hook around the trees that barely cleared the water.

Woods shot 74, ending his streak of 16 rounds at par or better at a major he won four times.

The final hole summed up his day, perhaps the tournament, and the state of golf as it prepares for the next generation. Woods was settling over his shot in the middle of the 18th fairway when McIlroy holed his big putt on the 17th.

For so many years, it was Woods who delivered big birdies that made everyone else take notice. This time, it was McIlroy who forced Woods to back off. He then hit his approach over the green and missed a 6-foot par putt, leaving him seven shots behind.

"I just made nothing," Woods said. "I hit the ball well all day. That wasn’t the problem. Take away the two three-putts there, a couple of unforced errors and it should have been a pretty good round."

McIlroy didn’t have to make any such excuses.

He has made only three bogeys over three rounds, and no three-putts, always a key at the Masters. He and Day were tied for the lead at 9 under as they made their way through Amen Corner, and McIlroy seized control on the 13th.

A bold tee shot down the left side, where Rae’s Creek winds its way along the azaleas, gave McIlroy a clear shot on the green and he two-putted for a birdie. Day attacked the flag in the back left corner and went long, into the second cut. His delicate chip rolled back toward him, he putted up the slope about 6 feet below the hole and missed the putt to make bogey.

Day fell further behind as McIlroy played well beyond his 21 years.

The Australian was saved on the par-5 15th when his shot came up short, but stayed dry because the grass is not shaved as low as it normally is. He was able to get up-and-down for birdie to match another two-putt birdie by McIlroy.

On the 16th, both were on the bottom shelf. Day gunned his putt about 6 feet past the hole and missed it coming back. McIlroy rolled his with better pace to pick up an easy par, and another stroke.

Then came the 17th, where McIlroy hooked his approach around the pines to the back of the green, then holed the slick putt that unleashed his emotions and set off the loudest roar of the day.

"It was a bonus," he said. "After I hit the tee shot, I would have just loved to walk away from that green with a 4 and moved on to the 18th tee. It was tracking the whole way and just dropped in the middle. It was great, because I had been waiting on a putt to drop all day, and for it to drop there, it was great timing."

It was the third straight day for McIlroy and Day to play in the same group. Saturday was different, though, and as both tried to get into position for a green jacket, there was a lot less chatter.

"I still went out there and had fun," Day said. "Obviously, I made a few disappointing choices. But I’m going to go out there tomorrow and I’ve got a game plan that I want to stick to. And if I can do that and hole some putts, hopefully I can try and chase them down."

Missing from the pack are the Americans. Bo Van Pelt was the low American after a 68 put him in eighth place, six shots behind. Woods was in the group seven shots behind along with 51-year-old Fred Couples and Bubba Watson.

If an international player wins, it will be the first time ever that Americans did not own any of the four majors or the Ryder Cup.