Brooks Koepka has said he regrets his comments during the US PGA Championship which appeared dismissive of some of his rivals.

Former US Open champion Dustin Johnson took a one-shot lead into the final round at Harding Park, with Koepka two shots behind in pursuit of an historic third straight victory in the event and a fifth major title in 11 starts.

Asked about his chances after the third round, Koepka told CBS: "A lot of guys on the leaderboard I don't think have won (a major). I guess DJ has only won one. I don't know a lot of the other guys that are up there."

Rory McIlroy admitted he was taken aback by Koepka's verbal dig at Johnson, but Koepka is more concerned about the "other guys" part of his comment, which would include eventual winner Collin Morikawa, Cameron Champ and Scottie Scheffler.

"Yeah, it's definitely that part because that's a shot at all the other guys," Koepka told Golfweek.

"We pretty much know everybody, we grew up playing golf with them and it came across that I had no idea who these guys are. And that's completely false.

"I honestly was struggling coming down the end of the third round. I was well back and I saw DJ was at minus 9. I birdied to get to minus 7. I was focused on Dustin. I had no idea who was at 8 or with me at 7.

"To be honest, when I'm looking at a leaderboard I'm never looking at who is behind me or tied with me, I only look ahead. I view myself as going forward no matter what.

"So I regret that part of it. That's what I was trying to say, that I didn't know who was on the leaderboard at that point because I hadn't looked. I just genuinely didn't know the guys at eight and seven (under).

"That part I regret and I wish I had used different words because I didn't pay enough attention to who was under Dustin because he was my main focus.

"When someone asks if I can win, I'm always going to say yes, that's the competitor in me. I'm not there to finish second. I think that's where some of the cocky stuff comes from because I always think I can win and truly believe it."

Koepka's comments backfired as he went on to card a closing 73 and finish in a tie for 29th, while Johnson finished joint second with England's Paul Casey.

"Obviously, a lot came from it," the four-time major winner added. "I don't mind the pressure of that stuff. I put more pressure on myself than anything external.

"At the same time, I didn't back it up. That's my own problem. Part of being someone who talks openly and truthfully is that sometimes I come off cocky or arrogant, and it can backfire if you're not going to play good. That's exactly what happened."