AUGUSTA, Ga. (AP) — Get ready for a "birdie-fest" at Augusta National.

Three-time Masters winner Phil Mickelson said the course he's loved and respected for decades is not yet its fearsome, soul-destroying self — and that has him worried.

"It seems that some of the planning I have made may go by the wayside," Mickelson said Tuesday. "As soft as the golf course is, you can fire at a lot of the pins."

That means a host of fearless, 20-somethings will whack away in the fairways with little concern for impediments like Rae's Creek or the tricky, closely mown slopes protecting the greens.

"Unless something changes," Mickelson predicted, "it's going to be a 'birdie-fest.'"

Mickelson is making his 20th appearance at the Masters, many of those spent learning each bump and bunker through pain-staking trial and error. It took several changes in his game and attitude before he finally broke through with his 2004 victory here.

Mickelson said one of the most drastic changes was how he approached the pivotal, par-5 15th hole, which has made as many Masters champions as it has ruined through the years.

Count Mickelson one of those waylaid by the daunting hole with the pond in front. Mickelson had played it for years as a "must birdie" hole, fearing anything else would drop him behind the field. That led to what Mickelson called some disastrous scores and the realization that something had to change.

"I think when you get hit in the head enough times, you look back and say, 'You know, maybe I should step back,'" Mickelson said.

These days, par is perfectly acceptable for Mickelson on the 15th.

"That's kind of what happened to me after just getting hammered by that hole so many times in the '90s that when I finally won in 2004, I just accepted the fact that it's hard hole," he said. "If I make four, great, but five is not bad."

Mickelson's Masters win in 2004 changed his attitude here forever. Gone were the questions about when he'd win a major, replaced by an unfettered excitement whenever the tournament nears.

"There was this burden of having never won a major. There was this burden of wanting to win the Masters so bad and being a part of the history of the tournament," he explained. "When I won in 2004, it was no longer pressure. It was excitement."

There figures to be plenty of excitement heading into Thursday's opening round.

World No. 1 Luke Donald, second-ranked Rory McIlroy, Mickelson and four-time champion Tiger Woods have won PGA Tour events in the run up to the Masters.

The soft conditions, Mickelson said, opens the door for players like McIlroy to make a barrage of birdies and run away and hide with this event the way he did in winning the 2011 U.S. Open.

"He plays without fear, which is a great way to play," Mickelson said of McIlroy. "When you get soft conditions like at the U.S. Open (last year), he's going to light it up."

McIlroy is seeking redemption from his back-nine meltdown at Augusta that cost him the tournament. Woods is also chasing a golf rebirth, hoping to add his first major title since 2008 — before a sex scandal tarnished his image.

Mickelson carries no such baggage into the season's first major. When he won here two years ago, the focus was as much on Mickelson's wife, Amy, and her fight against breast cancer. She was on hand to celebrate leaving a poignant picture in the minds of all who watched the couple embrace.

All's well with the Mickelson family, who'll join Phil this weekend then leave for a vacation in the Bahamas next week.

"It's cool to look back now on where we're at now and look back and think, you know, how far we've come," Mickelson said.

Mickelson hopes the preparation he's put in, plus the years of knowledge he's accumulated will pay off this week. He's also counting on the sun to kick in as well to dry up the greens and give them their trademark lightning speed that typically punishes aggressive play.

"If the green speeds get a little bit quicker and get a little bit firmer, I think we'll see some of the young players make some mistakes that will cost them the tournament," Mickelson said. "The experienced players who position the ball properly and vary their risk-reward shot making, I think they will have an easier time staying on the leaderboard."