Rory McIlroy has announced his withdrawal from next week's BMW PGA Championship due to a persistent rib injury.
The World No 2 has played in just six events in 2017 as he continues to feel the effects of a stress fracture to his ribs sustained earlier in the year.
While a recent MRI revealed he hadn't suffered a fresh injury, he continues to deal with a "low-grade response" to his previous setback.
"Having had a reaction to my earlier rib injury, I have been advised to take a conservative approach to my recovery which unfortunately means I have to withdraw from the BMW PGA Championship next week," McIlroy said.
"It's a disappointing decision to have to make, but I have to ensure I make a full recovery. I will now continue the process of preparing my game for the US Open and the rest of the season".
McIlroy's absence comes as a big blow to the European Tour's flagship event. He also pulled out last year, after missing the cut in his title defence in 2015.
"There is no question that Rory will be missed at the BMW PGA Championship, but his health is the most important thing and we wish him a speedy recovery," European Tour chief executive Keith Pelley said.
McIlroy is scheduled to appear at The Memorial from June 1-4, his last planned appearance ahead of next month's US Open at Erin Hills.