Justin Thomas has shown his support for Rory McIlroy by condemning ‘completely unacceptable’ fan behaviour at golf tournaments.

The support comes following an incident after the second round of Genesis Open where the four-time major winner McIlroy, competing alongside Thomas and Tiger Woods, said that volume from the galleries following them gave him a headache and that he needed “a couple of Advil”.

Speaking after finishing up his third round last night, reigning US PGA champion Thomas addressed the behaviour of certain fans.

“It was alright for a little bit today, there at the end it got a little out of hand. You know, I guess it's a part of it now, unfortunately," he said.

“I wish it wasn't, I wish people didn't think it was so amusing to yell and all that stuff while we're trying to hit shots and play. But like I said, it's just a part of it.”

He added: “I guess they just think it's funny. It might be funny to them, and obviously people think of it differently and I could just be overreacting, but when people are now starting to time it wrong and get in people's swings is just completely unacceptable really. 

“We're out here playing for a lot of money, a lot of points, and a lot of things can happen, and you would just hate to see in the future something happen down the line because of something like that.”

Tiger Woods, who missed the cut, has also echoed McIlroy’s and Thomas' comments, adding that distractions outside the ropes had affected his play at certain times.

“All it takes is one shot on a Thursday that you lose a tournament by a shot on Sunday.

“What people don't realise is it's not just something that happens on Sunday afternoon. This is cumulative and it's par for the course. I’ve dealt with it for a very long time.”

The Genesis Open continues today with McIlroy carding a two-over 73 to leave him level par for the tournament.