Japan's 2021 Masters winner, Hideki Matsuyama, has been disqualified midway through the first round of the 2022 Memorial Tournament in Ohio for using a club that appeared to be illegally altered.

The world number 12 was three over par through nine holes before being informed at the 10th tee of his violation of rule 4.1a, the use of a non-conforming club.

Chief referee Steve Rintoul said a substance that looked like correction fluid or paint had been applied to the surface of one of Matsuyama's clubs.

"Those markings were placed there by his club guy to help with alignment," Rintoul said.

"Assistance with alignment by placing a small Sharpie mark on the face is certainly allowed, but what was done there with that substance — which is very much like a Wite-Out substance we would use at home — was a coating that was not only in the grooves, but was very thick along the face … which renders the club non-conforming."

Rintoul said photos uploaded to the internet were brought to his attention after Hideki began the second hole, after which he approached Matsuyama for confirmation.

"Our committee became aware through some pictures that were posted that there may be a substance that has been painted on the face of one of Hideki's clubs," he said.

"A substance or any treatment can't be applied to the face of a club which could influence the flight of the ball, the spin, the loft, or anything on the ball — how the ball performs.

"The pictures were damning. It's very much like a Wite-Out you might use on a paper; a Wite-Out substance that was very much up on the face of the club which, really, it's very clear in the equipment rules that's not allowed.

"You can carry a non-conforming club, but you just can't use it under the new rules."

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After being questioned, Matsuyama admitted using the club at the start of the round.

"We tried to get to Hideki on the first round when we first heard about this," Rintoul said.

"We had one of our officials talk to Hideki on the second hole: 'Hideki, are you carrying this club?'

"'Yes'.

"'Hideki, have you used this club?' And that was unfortunately, 'Yes.' He'd used it off the first tee.

"So the use of a non-conforming club off the first tee meant disqualification."

Matsuyama, 30, won the first of his eight PGA Tour titles at the Memorial in 2014.

At the 2021 Masters, he became the first Japanese golfer to win a men's major championship.

Reuters/ABC