Bryson DeChambeau says he regrets his "unprofessional" comments regarding his golf equipment following his first round at the Open.
The 27-year-old claimed his Cobra driver was at fault for a one-over-par first round at the 149th Open Championship at Royal St George's.
"If I can hit it down the middle of the fairway, that's great, but with the driver right now, the driver sucks," said the American, whose fairways-hit percentage of 28.5% was about half of the field average.
Club manufacturers Cobra - who have designed the driver with a 46-inch shaft and only five degrees of loft specifically for DeChambeau - did not take kindly to the comments, however, calling them "stupid" and comparing the 2020 US Open champion's outburst to an "eight-year-old that gets mad".
With time to reflect on his post-round press conference earlier in the day, DeChambeau posted on Instagram to apologise for his rant.
"The comment I made in my post-round interview today was very unprofessional," he said.
"My frustration and emotions over the way I drove the ball today boiled over.
"I sucked today, not my equipment. Cobra and I have worked together for over five years and they are some of the hardest working people in the golf industry and make an incredible product.
"Their team is like family to me, especially Ben Schomin who has been there for me every step of the way since I started my career.
"I deeply regret the words I used earlier. I am relentless in pursuit of improvement, and perfection.
"Part of that causes me to become outwardly frustrated at times. With the new speeds I am obtaining, my game is a constant work in progress and so is controlling my emotions."
Cobra's tour operations manager Ben Schomin hit out at DeChambeau earlier in the day.
"Everybody is bending over backwards," Schomin said, who caddied for the player at the Rocket Mortgage Classic a fortnight ago, told Golfweek.
"We've got multiple guys in R&D (research and development) who are CAD'ing (compute-aided design) this and CAD-ing that, trying to get this and that into the pipeline faster. (Bryson) knows it.
"It's just really, really painful when he says something that stupid. He has never really been happy, ever. It's like an eight-year-old that gets mad at you. They might fly off the handle and say, 'I hate you', but then you go, 'Whoa, no you don't.'
"We know as adults that they really don't mean that and I know that if I got him cornered right now and said, 'What the hell did you say that for?' he would say that he was mad.
"He didn't really mean to say it that harshly. He knows how much everyone bends over backwards for him, but it's still not cool."