After a four-month hiatus, Phil Mickelson is ready to return to competitive golf, albeit on a "new path" and with a "fresh start" on the LIV Golf Invitational Series.

Mickelson, a six-time major championship winner, was added to the field on Monday for LIV Golf's first event, which is scheduled to start Thursday at Centurion Club outside London. In a statement posted to his Twitter account on Monday, Mickelson said he still plans to play in the majors, but didn't say whether he would compete in PGA Tour events.

Mickelson said he plans to play in the U.S. Open, which begins June 16 at The Country Club in Brookline, Massachusetts.

"I am looking forward to playing the U.S. Open and I'll be there," Mickelson told Sports Illustrated on Monday. "I'm under the understanding that I'm able to play."

Mickelson, 51, hasn't played since missing the cut at the Farmers Insurance Open in January. He skipped the Masters and PGA Championship, an event he won last year. He took time away from golf after his controversial comments about the PGA Tour's "obnoxious greed" and the Saudi Arabian financiers of LIV Golf caused a firestorm. Mickelson said he feels healthy and "more at peace" after being "engaged and intentional" in continued therapy.

"I am ready to come back and play the game I love but after 32 years this new path is a fresh start, one that's exciting for me at this stage of my career and is clearly transformative, not just for myself, but ideally for the game and my peers," Mickelson wrote.

"I also love the progressive format and think it will be exciting for fans. Just as importantly, it will provide balance, allowing me to focus on a healthier approach to life on and off the course. I am incredibly grateful for what this game and the PGA Tour has given me. I would like to think that I have given back as well but now I am excited about this new opportunity."

Mickelson joins a 48-man field in London that also includes two-time major winners Dustin Johnson and Martin Kaymer, as well as four other major winners: Sergio Garcia (2017 Masters), Charl Schwartzel (2011 Masters), Graeme McDowell (2010 U.S. Open) and Louis Oosthuizen (2010 Open Championship).

"Phil Mickelson is unequivocally one of the greatest golfers of this generation," LIV Golf CEO Greg Norman said in a statement. "His contributions to the sport and connection to fans around the globe cannot be overstated and we are grateful to have him. He strengthens an exciting field for London where we're proud to launch a new era for golf."

Mickelson, one of the most popular players of his generation, has already paid a steep price for his controversial comments. Several of his longtime sponsors, including Amstel Light, KPMG and Workday, ended their relationships with him. Callaway, which signed Mickelson to an equipment deal until the end of his career, paused its relationship with him.

Mickelson apologized for his remarks, which were made to author Alan Shipnuck, who was writing an unauthorized biography of the player popularly known as "Lefty." During the conversation, which Shipnuck said took place in November, Mickelson said he was working with two players to hire lawyers to draw up operating agreements for the new circuit, which is being financed by Saudi Arabia's Public Investment Fund.

"They're scary motherf---ers to get involved with," Mickelson told Shipnuck. "... They killed [Washington Post reporter and U.S. resident Jamal] Khashoggi and have a horrible record on human rights. They execute people over there for being gay. Knowing all of this, why would I even consider it? Because this is a once-in-a-lifetime opportunity to reshape how the PGA Tour operates."

Mickelson apologized for the remarks again on Monday.

"First and foremost, I want to again apologize to the many people I offended and hurt with my comments a few months ago," Mickelson wrote. "I have made mistakes in my career in some of the things I have said and done. Taking time away and self-reflecting has been very humbling. I need to start prioritizing the people that I love the most and work on becoming a better version of myself."

While many stars such as Tiger Woods, Rory McIlroy, Justin Thomas and Jordan Spieth have pledged their loyalty to the PGA Tour, Mickelson and 13 others are jumping to Norman's new circuit.

On May 11, the PGA Tour denied conflicting-event releases to players who requested them to play in London. Tour commissioner Jay Monahan told player agents at last week's Memorial in Columbus, Ohio, that players had to choose between the tour and LIV Golf and couldn't play on both circuits. Monahan has threatened players who competed in London without releases with discipline, including fines, suspensions and/or bans.

On Saturday, longtime PGA Tour member Kevin Na, who also is competing in London, resigned from the tour instead of facing possible discipline or legal action. Garcia, Schwartzel, Oosthuizen and Branden Grace also resigned from the tour, their manager told The Associated Press on Monday.

LIV Golf is offering staggering purses -- the total prize money is $255 million this year, including $25 million for each of the seven regular-season tournaments -- that are the richest in professional golf. The eight-event LIV series will feature five tournaments played in the United States, including a team championship match-play finale at Trump Doral in Miami from Oct. 28 to 30. The second LIV event is scheduled for July 1 to 3 at Pumpkin Ridge Golf Club in Portland, Oregon.