It was only 12 months ago that pandemonium erupted as Phil Mickelson made history by winning the US PGA Championship.

Mickelson sensationally became the oldest major champion at the age of 50, sparking incredible scenes at Kiawah Island.

Thousands of fans engulfed 'Lefty' on the fairway in South Carolina as he showed age is no barrier, and he gave a thumbs-up after emerging from the crowd, savouring a sixth major triumph that few would have predicted.

"One of the moments I'll cherish my entire life," Mickelson said. "I don't know how to describe the feeling of excitement and fulfilment and accomplishment to do something of this magnitude when very few people thought that I could."

What a difference a year makes.

Mickelson will not tee off at Southern Hills Country Club for the second major of the year on Thursday as he continues to take a break from golf.

The San Diego native has not played since he caused a storm by making controversial comments over the Saudi Arabia-backed LIV Golf Invitational Series. 

Mickelson stated that Saudi Arabia has "a horrible record on human rights", but added he was willing to commit to the breakaway tour as it was "a once-in-a-lifetime opportunity to reshape how the PGA Tour operates". He later apologised.

Greg Norman, figurehead for the LIV Golf Invitational Series, then slammed the "anti-golfer, anti-fan, and anti-competitive" PGA Tour for denying players from entering the opening the first event of the new league next month.

Mickelson, Sergio Garcia and Lee Westwood are among the players who asked to be released to play in the inaugural event at Centurion Club from June 9-11.

The PGA Tour stated they "would have welcomed [Mickelson] to participate" in Tulsa, Oklahoma this week, but it would surely not have been the warmest of welcomes.

Phil Mickelson

As the off-course rows rumble on, there is no doubt where the best players in the world want to be this week.

World number one Scottie Scheffler will go in search of back-to-back major triumphs after winning his first at the Masters and is well fancied to achieve that feat.

Tiger Woods is back in major action after making an amazing return at Augusta less than 14 months after he was involved in a car accident that left him with serious leg and foot injuries he sustained.

The legendary Woods says he feels "a lot stronger" than he did at the Masters and he will be guaranteed great backing once again.

An in-form Jordan Spieth looks primed for a strong challenge to achieve the career Grand Slam, with Lee Kyoung-hoon the only player to have beaten him since he missed the cut at Augusta.

Spieth won the RBC Heritage and was second behind Lee at the AT&T Byron Nelson last weekend.

Could this be the week in which Rory McIlroy wins his first major for eight years? The Northern Irishman finished with a flourish at Augusta to take second place and also heads into this tournament in ominous form.

Jon Rahm and Justin Thomas are among the other leading contenders at a course where the winner had at least a share of the lead in five of seven majors.

It promises to be another enthralling four days in the battle for the Wanamaker Trophy, a prize that Mickelson relinquished without striking a ball.