Brooks Koepka believes he will turn his form around despite still being troubled by a knee injury.

Koepka, the world number six, has missed two cuts in his past three events heading into the WGC-FedEx St. Jude Invitational.

The four-time major champion is confident he can recapture his best form, having recorded just one top-10 finish in 10 events this year.

“It’s definitely been frustrating. It will test you mentally, but at the same time, I’m looking at it as a challenge and something where I know it will turn around eventually. It’s going to turn around,” Koepka told a news conference.

“You don’t work that hard for nothing. Starting to see signs of it. Now it’s just about going and doing it.

“Whether it be this week, next week, a month from now, two months from now, whatever it’s going to be, it will pay off.”

Koepka suffered a torn patella tendon in his knee last year and is still being bothered by the injury.

The American said he would finish the season before considering his options.

“The tear has to be worse to go under the knife, but we’ll see how it goes,” Koepka said.

“We’ll see when my season ends and go get stem cell again most likely and figure it out from there.”