KIAWAH ISLAND, S.C. – Though he wasn’t looking to make excuses, Dustin Johnson said his right knee has flared up on occasion over the past six months.

That at least partly explains the world No. 1’s dip in form.

Johnson had arthroscopic surgery on his right knee in fall 2019 but started to experience discomfort again over the past few months. It bothered him enough to the point that he withdrew from last week’s AT&T Byron Nelson to undergo an MRI and receive more treatment. He said the exam came back clean, and he reported feeling “really good coming into this week.”

“It just didn’t feel right,” he said Wednesday on the eve of the PGA Championship. “Everything was fine. Just got together with the doctor and physio down there (in South Florida) and put together a little bit of a plan to get a little bit stronger. It feels good, though.”

Johnson won the Masters last November to cap one of the most impressive stretches in recent memory. Though he won earlier this year in Saudi Arabia, he hasn’t been able to sustain that elite level of performance. He has now gone six consecutive starts without a top-10, his longest drought since summer 2019 – when, ironically enough, he was also dealing with right-knee pain that later required surgery.

“It’s been a mix of everything,” he said when explaining his recent slide. “But the game feels good. I feel like it’s been close the past few months; just haven’t put it all together at the same time. But everything feels really good right now. I’ve got a lot of confidence coming into this week. I feel like I’ve been working hard on the game and looking forward to it.”

The runner-up at the PGA the last few years, Johnson’s No. 1 ranking could be in danger this week. Justin Thomas would ascend to the top spot if he wins at Kiawah Island and Johnson finishes worse than solo fifth.