This is the 20-year anniversary of Jack Nicklaus’ stunning back-nine charge to win his sixth green jacket at age 46. Couples was poised to become the oldest Masters champion — 46 years, six months — and he hung with Mickelson until his putter betrayed him.

First came a three-putt on the 11th, his 3-foot par putt spinning around the cup. On the 14th hole, Couples had a 4-foot birdie putt to pull within one shot. It caught the lip and spun 6 feet away, and he missed that one, too.

“I didn’t hit the ball like I was 46,” Couples said. “I putted like I was 66.”

Mickelson poured it on with an eagle chip that caught the lip on the 15th, and steady pars the rest of the way until the 18th.

Then it was off to Butler Cabin, where Woods slipped the green jacket on Mickelson’s shoulders.

“Great playing,” Woods told him.

If Woods bothers to watch the highlights, it should look awfully familiar.

The last time Augusta National was overhauled to add length, Woods built a big lead and let an All-Star cast of contenders collapse around him with shots into the woods and the water.

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The course was stretched even more for this Masters — at 7,445 yards, the second-longest in major championship history. Mickelson played it impeccably. The longest par putt he had all day — besides the meaningless one from 20 feet that he missed on the 18th hole — was the 5-footer he made after a solid bunker shot on the 10th.

“I think what I’m most proud of is that I didn’t let other people back in it,” Mickelson said. “They had to come chase me down and make birdies to do it.”

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Mickelson won for the 29th time on the PGA Tour, tying him for 17th on the career list.

And he became the first Masters champion since Sandy Lyle in 1988 to win the week before coming to Augusta. Mickelson captured the BellSouth Classic last week by 13 shots.

This one was closer, but it sure didn’t seem that way.

He took a one-shot lead into the final round by making the fewest mistakes Sunday morning, when the rain-delayed third round was completed in cool, mostly calm conditions. Mickelson shot 70 and was at 4-under 212, the highest 54-hole score to lead the Masters since 1989. Couples shot 72, making two birdies on the final four holes to get into the final group.

MULTIPLE MASTERS TITLES Player Years Jack Nicklaus 1963, '65, '66, '72, '75, '86 Arnold Palmer 1958, '60, '62, '64 Tiger Woods 1997, 2001, '02, '05 Jimmy Demaret 1940, '47, '50 Nick Faldo 1989, '90, '96 Gary Player 1961, '74, '78 Sam Snead 1949, '52, '54 Seve Ballesteros 1980, '83 Ben Crenshaw 1984, '95 Ben Hogan 1951, '53 Bernhard Langer 1985, '93 Phil Mickelson 2004, '06 Byron Nelson 1937, '42 Jose M. Olazabal 1994, '99 Horton Smith 1934, '36 Tom Watson 1977, '81

The possibilities were endless.

Ten players were within three shots of the lead, a list that included Woods and Singh. Ten more were within five shots of Mickelson.

But no one did anything to bring Augusta National to life.

There was a five-way tie for the lead early in the final round — Mickelson, Couples, Campbell, Rocco Mediate and Miguel Angel Jimenez — all at 4 under before making the turn. But it didn’t last.

Mickelson took the outright lead with a long pitch to the par-5 eighth that checked up 2 feet behind the hole for birdie, and everyone else either stalled or spiraled, none worse than Mediate. He hit three balls into Rae’s Creek on the par-5 12th — two from in front of the green, one from the bunker behind it — and made 10.

Campbell had a three-putt bogey on the 11th and hit into the water on the 15th trying to reach the green in two. Jimenez fell out of the chase with bogeys on the 10th and 12th, and Clark was lurking until a bogey from the bunker on the 12th.

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Mickelson was untouchable, as Woods was in 2002 after the first big course renovation.

And in the final act of this Masters, their roles were reversed in Butler Cabin, the way Nicklaus and Arnold Palmer swapped Masters titles 40 years ago.

“I really don’t want to trade next year,” Mickelson said. “I certainly enjoyed the jacket put on me.”