Rory McIlroy has said a players' lounge full of professionals immediately questioned Bryson DeChambeau's grass trampling at Royal Birkdale on Friday, after the American received a two-shot penalty during the second round of The Open Championship.

McIlroy said the incident was clear enough to draw instant concern from those watching, before DeChambeau's extended dispute with officials delayed the release of Saturday's tee times.

DeChambeau was called in by rules officials after playing the fifth hole, a par four, during his second round. The ruling found that he had improved the conditions affecting his next shot by stepping into long grass around the ball before striking it.

There was no suggestion that DeChambeau deliberately tried to improve his lie. Yet golf's rules do not require officials to establish intent in such circumstances.

The practical question is whether a player has altered the conditions around the ball. Officials concluded that he had.

The penalty shifted the leaderboard sharply. DeChambeau had stood second, one stroke behind 36-hole leader Lucas Herbert, before slipping into a tie for fifth once the two strokes were added.

McIlroy, speaking after his own round, did not hide his view of either the ruling or DeChambeau's response. He said he had been watching in the players' lounge with several fellow competitors when the moment occurred.

'As soon as he made the step into the ball, we all sort of looked at each other, and we were like, 'That didn't seem right,' McIlroy said.

No forensic replay was needed for the players watching from inside Royal Birkdale. In McIlroy's telling, the reaction was immediate and shared.

Rory McIlroy insists a painful toe blister will not hinder his PGA Championship bid at Aronimink after a brief practice scare and a swift change of footwear. Bryan Berlin, CC BY-SA 4.0 , via Wikimedia Commons

He went further, saying there was 'no doubt' that DeChambeau had improved the line of his backswing. Whether the action was careless or intentional, McIlroy argued, was beside the point. 'Hopefully, it was careless,' he said, adding that the two-shot penalty was justified.

It is the sort of technical ruling that can leave casual viewers cold. But in plain terms, a golfer cannot press down, move or otherwise improve grass around a ball if doing so makes the next stroke easier.

The rule is designed to protect the basic bargain of the sport. Play the course as you find it, even when the course has handed you some rough stuff.

The rules decision did not end when DeChambeau left the fifth hole. According to the supplied report, he exchanged heated words with officials, then went to the practice range as darkness fell with a large group of reporters following him.

His continuing objections delayed third-round tee times, leaving players, volunteers and tournament staff waiting for clarity. McIlroy called that sequence a poor look, accusing DeChambeau of holding the championship 'hostage.'

Television footage showed Bryson DeChambeau moving long grass behind his ball before making his swing, prompting officials to review whether he had improved the conditions affecting his stroke. Jacob Gralton, CC BY-SA 2.0 , via Wikimedia Commons

'Late night for everyone,' McIlroy said. 'I won't pretend to be up here and defend Bryson. I'm not particularly fond of him. I think a lot of it's performative. I think a lot of it's for attention.'

It was unusually blunt, even by the sometimes chilly standards of elite golf. McIlroy's criticism was not only about a disputed step in the rough.

He appeared irritated by the spectacle around it, and by the sense that one player's fight with a ruling had begun to dictate the timetable for everybody else.

DeChambeau's representative, Brett Falkoff, initially would not confirm whether his client would start the third round. DeChambeau later said on social media that he would continue, writing that he was disappointed with the decision and did not agree with it, but that it had fired him up for the weekend.

Nothing is confirmed yet so everything should be taken with a grain of salt.

McIlroy, meanwhile, carded a 69 to move to two under par for the tournament. He was six strokes behind clubhouse leader Ryan Fox and said he did not see himself as having a great chance to win, unless he could reach double digits under par in the third round.

DeChambeau was still in contention too. The penalty had changed his position, not ended his week. In a major championship, that distinction can matter rather a lot.