Koepka was asked again Tuesday at The Open about their ongoing feud, and the four-time major winner said he's fine keeping it going because DeChambeau went back on his word about an agreement they had, so now he's "fair game."
Their differences were highlighted again two months ago when a taped interview of Koepka showing his disgust for DeChambeau was leaked and went viral. There has been a good bit of back and forth since, all of it starting with Koepka's slow-play complaints about DeChambeau in 2019.
Koepka said the deal they made came during a discussion at the 2019 Northern Trust tournament at Liberty National in Jersey City, New Jersey.
"We had a conversation at Liberty, and he didn't hold up his end of the bargain and I didn't like that, so I'll take my shots," Koepka said.
He then went on to explain how it went wrong.
"He didn't like that I had mentioned his name in slow play, so we had a conversation in the locker room," Koepka said. "And then I guess we said something else in the press conference but didn't mention his name in it, and he walked up to [Koepka's caddie] Ricky [Elliott], said something. It was, 'You tell your man if he's got something to say, say it to myself.' I thought that was ironic because he went straight to Ricky. Ricky told me when I came out, hit a few putts, and then just walked right over to him, we had a conversation.
"We both agreed we'd leave each other out of it and wouldn't mention each other, just kind of let it die off, wouldn't mention each other's names, just go about it. So then he decided I guess he was going on that little, whatever, playing video games online [on Twitch in which he made light of Koepka appearing in ESPN's The Body Issue] or whatever and brought my name up and said a few things, so now it's fair game."
DeChambeau also spoke on the matter on Tuesday.
"He can say whatever he wants,'' DeChambeau said. "I think he said something back at Liberty National not upholding something. I don't know what he's talking about in that regard. Maybe that's on me. Maybe I didn't. I really don't remember anything about that. We just had a conversation that I really don't know what happened, because we haven't really bantered back and forth until now, so it's like why is that happening now.
"Besides that, I'm just here to play golf and focus on that. If we want to keep bantering back and forth, obviously being respectful and keeping lines where they aren't getting crossed, yeah, I think it's fun and a good environment for people in golf.''
Koepka said there would be no issues with DeChambeau as a teammate at the Ryder Cup in September.
"It's only a week," he said. "I can put it aside for business. If we're going to be on the same team, I can deal with anybody in the world for a week. I'm not playing with him. I'm pretty sure we're not going to be paired together; put it that way. I think it's kind of obvious.
"It doesn't matter. I don't think we're going to be high-fiving and having late-night conversations. I do my thing, he does his thing. Yeah, we're on the same team, but it's not an issue at all. I don't view it as an issue. I don't think he does."
Koepka, who is ranked eighth in the world, has been in the top 5 in three of his past four appearances, including a tie for second behind Phil Mickelson at the PGA Championship and a tie for fourth at the U.S. Open behind Jon Rahm.
He got his first look at Royal St. George's on Tuesday and was not overly impressed.
"Quite a few blind tee shots, kind of hitting to nothing," Koepka said. "Fairways are quite undulating. I don't know, it's not my favorite of the [10-course] rotation, put it that way.
"[But] I don't care whether I like the place, don't like it. You've still got to play good and go hit the shots. Playing St. Andrews is probably my favorite place in the entire world to play. Portrush two years ago was ... I love that place. I thought that was just such a good Open. A fun golf course to play. Really enjoyed that.
"This one, it's just not as exciting. I don't know why. Whether it be a couple shots to nothing, a couple blind tee shots or shots in where you can't really see much. I'm not too big of a fan of that."
Koepka, 31, is making his seventh appearance at The Open, his last finish a tie for fourth in 2019 at Royal Portrush. He also tied for sixth in 2017 at Royal Birkdale.