Koepka, right, says he would be delighted to be paired with DeChambeau, left, in the final round this Sunday

Brooks Koepka has wasted no time in dialling up his bitter feud with Bryson DeChambeau before the 149th Open at Royal St George’s, insisting that he considered his nemesis “fair game”.

His hostility towards DeChambeau has been one of the compelling subplots of the golfing year, memorably captured by a video of the moment he heard his rival apparently joking about his problems at the USPGA. “I f—— lost my train of thought, hearing that b——,” he said at the time.

Here on the Kent Coast, the four-time major champion needed no second invitation to explain exactly why he could not tolerate his eccentric rival. Koepka traced the antagonism back to an incident at the 2019 Northern Trust in New Jersey, where he attempted to broker a rapprochement with DeChambeau after dragging his name into a row about slow play.

Koepka accused his fellow American of reneging on that peace deal, saying: “He didn’t hold up his end of the bargain and I didn’t like that, so I’ll take my shots.” Koepka has been firing off plenty such shots of late, even offering his fans free beer if they continued taunting DeChambeau on the course.

“He didn’t like that I had mentioned his name in slow play,” Koepka explained. “So he walked up to Ricky [Elliott, Koepka’s caddie] and said, ‘You tell your man if he’s got something to say, say it to me.’ I thought that was ironic because he went straight to Ricky. I just walked straight over to him and we had a conversation.

“We both agreed we would leave each other out of it and wouldn’t mention each other, let it die off. So then he decided, playing video games online or whatever, to bring my name up.” Specifically, DeChambeau ridiculed Koepka parading his body for a US magazine, joking: “He doesn’t have any abs.”

For one who takes such pride in his musclebound physique as Koepka, this was as flagrant a violation of their peace treaty as could be imagined. “Now it’s fair game,” he said on Tuesday, with a smirk. As for the likely dynamic between the pair at the Ryder Cup in Wisconsin in September, he suggested it would be sub-Arctic.

“I’m pretty sure we’re not going to be paired together, put it that way,” he said. “I think it’s obvious. We’re not going to be high-fiving or having late-night conversations. I do my thing, he does his thing.”

There are suspicions of a pantomime element to this row, given that PGA Tour players are financially incentivised for increasing the game’s exposure on social media. But Koepka reassured that the disdain was genuine. He also left no doubt as to how much he would love being paired with DeChambeau in Sunday’s final round of the Open, should both these major winners perform to their full potential.

“I would enjoy it,” Koepka said. “I’ll be close to the final group come Sunday. I think there would be a lot more people tuning in, with everything that has gone on over the last two years.”