Bryson DeChambeau has apologised to club manufacturer Cobra after saying his driver "sucks" on a tough first day at The Open.

Former U.S. Open champion DeChambeau acknowledged he was "very unprofessional" and his emotions "boiled over" at Royal St George's, where he signed for a one-over 71 as the 149th Open Championship got under way on Thursday.

The American – renowned for his big hitting – had been particularly dismayed by his underwhelming performance with his driver.

DeChambeau hit four of 14 fairways, a rate of 28.57 per cent well down on the field average of 56.23 per cent. Three players were tied for the category lead of 85.71 per cent.

Speaking after his round, the 27-year-old – at the centre of a public, persistent row with Brooks Koepka – said: "If I can hit it down the middle of the fairway, that's great, but with the driver right now, the driver sucks.

"It's not a good face for me, and we're still trying to figure out how to make it good on the mishits. I'm living on the razor's edge, like I've told people for a long time."

These comments prompted a strong response from Ben Schomin, Cobra's tour operations manager who caddied for DeChambeau at the Rocket Mortgage Classic after a split with long-time caddie Tim Tucker.

Schomin told Golfweek: "Everybody is bending over backwards. We've got multiple guys in R&D who are CADing this and CADing that, trying to get this and that into the pipeline faster.

"He knows it. It's just really, really painful when he says something that stupid.

"He has never really been happy [with his driver], ever. Like, it's very rare where he's happy."

Schomin went on to describe DeChambeau as "like an eight-year-old that gets mad at you", suggesting an apology would follow, although the criticism was "still not cool".

Sure enough, DeChambeau took to his Instagram page late on Thursday in an attempt to make amends.

"The comment I made in my post-round interview today was very unprofessional," he wrote. "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."

Thursday's result means DeChambeau is still yet to score below 70 at The Open, where he is hoping to finish in the top 50 for the first time.