Brooks Koepka gave the Saudi-backed LIV Golf circuit a landmark triumph and sparked some questions for the US Ryder Cup team by winning the PGA Championship on Sunday.

Koepka's fifth major title made him the first player to win a major since joining the breakaway circuit and boosted him to second in the US Ryder Cup qualifying points table.

"I definitely think it helps LIV," Koepka said.

Koepka was among the array of stars who jumped from the PGA Tour to LIV, which lured talent with the promise of record $25 million purses for 54-hole events, despite concern over Saudi Arabia's human rights record.

The PGA banned LIV players from its events, with a legal fight between them due in court next May. Until then, the rival circuit's top talent only meets in majors.

When asked if he takes pride in representing LIV, Koepka said, "Yeah, I think so. To win a major is always a big deal no matter where you're playing. All it does I guess, validates it for myself… I'm back."

LIV events don't get world ranking points, causing concern that major qualifying will be difficult soon. Koepka's win helps make the case their players deserve consideration.

LIV's Bryson DeChambeau shared fourth and reigning British Open champion Cam Smith shared ninth at Oak Hill. And Koepka shared second last month at the Masters with LIV's Phil Mickelson.

"Congrats @BKoepka your comeback has been impressive. I am so proud of you," LIV Golf League commissioner Greg Norman tweeted.

"As for the @livgolf_league players they belong and the Majors and golf knows."

US Ryder Cup captain Zach Johnson said he hasn't spoken to anyone about having LIV players on the squad, overseen by the PGA of America, which allowed LIV qualifiers into the PGA Championship.

"I think it's too premature, frankly irresponsible, to even have any sort of opinion about that," Johnson said.