It was 20 years ago when Phil Mickelson curled in an 18-foot birdie putt on the 18th green at the Augusta National Golf Club to win the 2004 Masters Tournament. It remains one of the most popular victories in golf history, the end of Mr. Mickelson’s painful zero-for-46 drought in majors and the first of six major championships in his Hall of Fame career.

The photo of Mr. Mickelson leaping in the air, his arms stretched over his head, and his feet spread airborne in triumph is iconic and serves as his logo. His open mouth and look of shock and relief convey his unbridled joy at winning the first of what would be three Green Jackets.

“First of all, the photographer did not get me at the apex and didn’t do it justice,” Mr. Mickelson said to a group of press last week, including the Sun. “I’ve thought that for 20 years and tried to recreate it and thought, well, maybe he did get me at the apex.”

“Finally Phil,” was the headline in the Augusta newspaper the next morning. The exact word Mr. Mickelson likely told himself, “Finally.”

This was seven years after Tiger Woods won his first of five Green Jackets while playing in his first Masters as a pro in 1997, and 13 years after Mr. Mickelson took the golf world by storm, winning a PGA Tour event as a left-handed amateur.

Mr. Mickelson, now 53, is back at the Masters this week, back at Augusta National where golf will get as close to a new normal as it can these days. His win here in 2004 led to repeats in 2006 and 2010.

“It was a relief,” Mr. Mickelson said in recalling the day he claimed his first Green Jacket. “I had said for a while going in that once I win one, I’ll win a bunch. I don’t know if six is a bunch but it’s more than one and that win validated what I was doing as being right. It gave me a lot of confidence that I could do this more often.”

Mr. Mickelson, annually invited to the Masters as a past champion, will have a new caddie in Jon Yarbrough when the first round begins Thursday. Mr. Mickelson’s brother Tim, who caddied for him since 2017, retired. “I’m very lucky to have had him on the bag for me the past eight years and as my brother for life,” Mr. Mickelson said in a statement.

The Masters is the first of the four majors where PGA Tour members will play alongside LIV Golf loyalists like Mr. Mickelson and defending Masters Champion Jon Rahm. Ideally, it would be a time when the two sides put their differences and controversies aside to focus on the competition for one of golf’s most cherished prizes. Yet there is bound to be talk of the ongoing negotiations between PGA Tour officials and Saudi Arabia-backed LIV Golf on some type of co-existence. No one seems to have any idea what that’s going to look like if it ever happens.

As one of the first to abandon the PGA Tour for LIV Golf, Mr. Mickelson has been the target of criticism and praise. A biography, “Phil: The Rip-Roaring Biography of Golf’s Most Colorful Superstar,” by Alan Shipnuck also highlighted associations with alleged gamblers. The heavy backlash from PGA Tour loyalists erased all the luster from becoming the oldest winner of a major when, at age 50, he claimed the 2021 PGA Championship at Kiawah Island.

Only this is Masters Week. Mention Augusta and the Masters and Mr. Mickelson smiles. Despite the adversity and the vitriol he has faced, his spirits and his game come to life when he plays in the Masters. At age 52, he finished tied for second last year, four strokes behind Mr. Rahm. Mr. Mickelson hasn’t done much on the LIV Golf circuit this year, but it’s clear he thinks he can still win here.

“It’s a course where I feel I don’t have to be perfect,” Mr. Mickelson said. “When I go through the gates and drive down Magnolia Lane, I relax a little bit because if we miss it on the right side of the hole, given the pin placement, if we miss in the correct side we can still salvage par utilizing our short games.”

Few have had a better short game than Mr. Mickelson, a magician with a wedge and impossible lies. “The recovery shots there are so exciting because the trees are high enough where you have a swing as opposed to taking an unplayable lie and wedging out,” he said. “I think that adds to a lot of the drama of Augusta.”

Few know the secrets of Augusta as intimately as Mr. Mickelson. Ask him to share some tidbits, and it’s like turning on a faucet with no shut-off value. He knows where the putts break, knows where he can be aggressive, knows where left-handers have advantages over right-handers and knows when to use a cut spin or a shot that checks up.

“There are little subtleties and nuances that allow that course to play differently for Bubba (Watson) and myself than Jon,” Mr. Mickelson said. “They can be aggressive on certain spots where we have to be a little bit more careful and vice versa.”

Mr. Mickelson is one of 13 LIV golfers in the Masters, and one of seven to claim a Green Jacket. The golfers might tell you the Masters is more of an individual event than about LIV and the PGA Tour, but the unofficial competition is still there. Mr. Rahm won last year as a member of the PGA Tour before joining LIV Golf in December for a reported $350 million.

The governor of Saudi Arabia’s Public Investment Fund, Yasir Al-Rumayyan, met with the PGA Tour commissioner, Jay Monahan, and members of the Tour’s policy board, which includes Tiger Woods, in the Bahamas last month and negotiations on some type of merger are reportedly continuing.

Mr. Mickelson offers no insight into the discussions, willing to sit on the sidelines after becoming a polarizing figure for saying LIV Golf would change how golf operates. He wasn’t wrong. “I knew the first two years were going to be interesting,” Mr. Mickelson said. “And how it all plays out, where it ends up, I don’t know exactly. I just know that in the end, it’s going to be a more global sport and there’s going to be more opportunities.”

He insisted his primary interest is to grow the game with an audience that might not be familiar with golf. “How do we get golf to people that don’t play golf,” he said. “That’s one of the challenges that’s quietly being addressed with ideas and so forth. I think there’s going to be some things that will appeal in the end to people that don’t necessarily play that want to watch and be interested in the game.”