The PGA Championship is set to tee off in just two days, though a notable name will be missing from the grounds at the Southern Hills Country Club. Last year's champion Phil Mickelson, who was initially listed as a member of the field, chose to withdraw from the PGA Championship, with the reason behind his decision unknown. Fellow golf star Rory McIlroy spoke out about Mickelson's decision and his absence from the PGA Championship, as reported by ESPN.

“This should be a celebration, right?” McIlroy said. “He won a major championship at 50 years old. It was possibly his last big, big moment in the game of golf. I think he should be here this week and celebrating what a monumental achievement he achieved last year.”

McIlroy paused as he weighed how his words would be received.

“It's unfortunate,” he said. “It's sad. Yeah, I don't know what else I can say.”

McIlroy feels that Mickelson “should be” at Southern Hills and that it “should be a celebration.” The 50-year-old became the tour's oldest major champion when he won the PGA Championship last year, finishing six-under to secure his sixth major.

While it is “unfortunate”, as McIlroy said, it's still Mickelson's own doing, as he made some questionable comments about the rival Super Golf League while criticizing the PGA Tour.

While Mickelson's absence will be felt at the PGA Championship, he ultimately has himself to blame for his inability to defend last year's title.

It will be up to Mickelson to rectify what has been a troubling last several months.