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.

Forget Johnson's six captain's picks. Right now Koepka has a spot on qualifying points, mostly gained from PGA Tour events.

"I'm just trying to prove it to myself, not trying to prove it to anybody else, that I can still do it," Koepka said. "I like the way things are starting to come together."

The Americans haven't won the Ryder Cup on European soil since 1993 at The Belfry in England and new world number one Scottie Scheffler wants to end the drought in Italy this year no matter who is playing where.

"I don't care about tours or anything like that. I want to win the Ryder Cup," Scheffler said. "We want to beat those guys in Europe. It has been a long time.

"We want a team of guys that are going over there together to bring the Cup back home and that's all I really care about."

Johnson meanwhile says while team chemistry is important, no one has said to him they are uncomfortable with LIV talent on the US team.

Johnson also said he has not spoken with Koepka about the US team but is impressed with him.

"He's an amazing player," Johnson said. "What I appreciate about Brooks is just how he goes about his work in massive tournaments. He's a rare breed mentally where he just is able to bring out his best in the most difficult and trying of circumstances."

Johnson doesn't plan to attend LIV events to analyze talent as he does PGA Tour events.

"I'm not one that's ever to say never but it's not been discussed," he said. "I'm still relevant and prevalent out on the PGA Tour.

"To abandon that, where the bulk of my players are certainly going to come from… would be irresponsible on my behalf and inappropriate."

Asked about watching LIV event on US television network CW, Johnson didn't know they were on TV.

"I have to ask my kids," he said. "I think I get the CW."