After some lighthearted banter on Twitter following the announcement that Tampa Bay Buccaneers quarterback Tom Brady and Phil Mickelson would take on Green Bay Packers quarterback Aaron Rodgers and DeChambeau this summer in the fourth edition of The Match, Koepka decided to enter the fray.
"Sorry bro @AaronRodgers12," Koepka tweeted in an obvious reference to Rodgers being paired with DeChambeau.
DeChambeau then offered a direct response to Koepka: "It's nice to be living rent free in your head!"
The exchange between Koepka and DeChambeau occurred after prodding from Brady, who playfully taunted DeChambeau and Rodgers by creating memes with a screenshot from a leaked viral video in which Koepka rolled his eyes at DeChambeau and cursed in frustration during an interview at the PGA Championship.
DeChambeau responded to one of Brady's posts by referencing the "Deflategate" scandal.
"@TomBrady, once @AaronRodgers12 and I take down you and @PhilMickelson, you will feel just as deflated as those balls were in the AFC Championship Game," DeChambeau wrote.
Mickelson, who became the oldest major winner in golf history with his victory at the Ocean Course on Sunday, used Wednesday's exchange to take a playful jab after the response from Koepka, who tied for second behind Mickelson at the PGA Championship.
"I feel like I'm in the middle of something and should step aside. (Except they want the current PGA champ)," Mickelson tweeted.
Shortly after, DeChambeau joined the spat with his message for Koepka.
The intense rivalry between Koepka and DeChambeau dates back a few years and heated up in January 2020, when DeChambeau mocked Koepka for his physique. Koepka chirped back on social media by referencing his four major titles.
DeChambeau, who won last year's U.S. Open, hadn't won a major at the time of the dispute.
The pair also clashed at the 2019 Northern Trust, when Koepka was one of multiple players to criticize DeChambeau for slow play.