A leaked video shows Koepka rolling his eyes at DeChambeau and cursing in frustration during a postround interview this past weekend at the PGA Championship.
The viral video, posted Monday night to social media platforms, is a clip from a Golf Channel interview after Koepka's second round Friday at Kiawah Island. As Golf Channel reporter Todd Lewis prepares to begin the interview, Koepka looks to his right before an exaggerated roll of the eyes.
Then as Koepka answers Lewis' question about his round, DeChambeau walks behind him in the shot, a move that left Koepka annoyed and distracted.
"I didn't putt well, but I don't think any of the guys were going to putt well with this wind," Koepka says before DeChambeau walks behind him. "It's very tough. I don't know what the other guys have said, I just found it difficult to read sometimes."
At that moment, DeChambeau and another man are seen walking in the background of the shot. It is unclear whether DeChambeau says anything, but Koepka stops speaking and closes his eyes in frustration before trying to continue his answer.
"Sometimes, um -- I lost my train of thought," Koepka admits. "Hearing that bulls---."
Golf Channel never published the interview and had not commented on the leaked video as of Tuesday morning.
Koepka carded a 1-under-par 71 on Friday after an up-and-down round that included two eagles and four bogeys. He was near the top of the leaderboard all weekend but ultimately finished tied for second with Louis Oosthuizen, 2 shots behind Phil Mickelson, who at age 50 became the oldest player to win a major in golf history.
DeChambeau struggled Sunday with a final-round 77 and finished at 3 over, 7 shots behind Koepka and 9 behind Mickelson.
The rivalry between Koepka and DeChambeau dates back a few years and intensified in January 2020, when DeChambeau poked fun at Koepka's physique. Koepka barked back on Twitter by pointing to his four major championships; DeChambeau, who won last year's U.S. Open, had not won a major at the time.
The golfers also clashed at the 2019 Northern Trust, when Koepka was one of several players to criticize DeChambeau for slow play.