Phil Mickelson has decided not to defend his US PGA title at Southern Hills next week.
The legendary American became the oldest major winner in history when he prevailed at Kiawah Island 12 months ago, collecting his sixth major crown in the process.
However, the 51-year-old said in February that he was taking a break from the sport after being heavily criticised for comments made regarding the LIV Golf International Series, which is being financially backed by Saudi Arabia.
Mickelson had initially been named on the entry list for the second major of the year, but tournament organisers have now said that the left-hander will not compete in Oklahoma.
A statement from the PGA of America said: "We have just been informed that Phil Mickelson has withdrawn from the PGA Championship.
"Phil is the defending champion and currently eligible to be a PGA life member and we would have welcomed him to participate. We wish Phil and [wife] Amy the very best and look forward to his return to golf."
Mickelson may now look to participate in the first LIV Golf International Series event at the Centurion Club in England next month, despite the PGA Tour formally rejecting requests from several players to feature in that competition.