Attempts to revive him were made before he was rushed to hospital, but he never regained consciousness, club president Hans Sauer told The Sydney Morning Herald.
Devastated friends, family and colleagues hoped an autopsy would show why Mr Denton died.
Mr Sauer said it was unusual for Mr Denton to take himself off to bed saying he was feeling unwell.
"We were absolutely shocked. We had no idea why he died."
Tributes flowed yesterday for Mr Denton, who was described as an outstanding young man and a highly respected leader.
His flatmate, a former Dunedin Rugby Club team-mate Richard Naylor, who was in Bali with Mr Denton, told The West Australian newspaper he had lost his best mate.
"I just loved him with all my heart. He was a keen sportsman and always gave 100 per cent in everything he did. He's the most amazing guy and I cannot speak highly enough of him."
Mr Denton had been in Bali for a day before his death.
Mr Naylor said it was his friend's first visit to Bali and he had been excited.
He said his friend had not been injured and nothing had seemed wrong before the Friday evening. He did not want to speculate on what happened.
"Until the tests are done, no-one knows what occurred. My heart goes out to his family - who he was very close to - and Dents is going to be greatly missed by anyone he's crossed paths with."
Mr Sauer said Mr Denton was considered a great leader among his peers, the junior players and old boys at the club.
"He was just one of those guys who was incredible around the club."
Rugby West Australia chief executive Vern Reid said the West Australian rugby community had been hit hard by the death of Mr Denton, who, he said, was a talented and dedicated player.
His boss at LandCorp described the project manager as charismatic and a great organiser.
Ross Hanson, who coached Mr Denton when he was with the Dunedin Rugby Club, and who was a friend of the Denton family, described Mr Denton as an outstanding young man.
"He was a very personable, open fellow and a great team member. I had enormous respect for him and do for his whole family."
Mr Denton would be greatly missed by the Dunedin Rugby Club and the whole Dunedin community, Mr Hanson said.
In a tribute posted on the Nedlands Rugby Union Football Club website, the club offered its condolences to the Dentons.
"We remember Michael Peter Denton for allowing us time to enjoy his company, his humour, his dedication, his commitment to the team and club.
"Dents, you have the total respect of everyone at Neddies, you are a champion and a true leader. Rest in peace brother, you will always live on at our club. We love you."
His sister Louise Denton, who flew home to Dunedin from Toronto to be with her family, said her brother had been described perfectly in the tributes. She, her three brothers and their mother Ruth hoped to have Mr Denton's body home this week, and a service would be held next week.
The family had had no news yet about what had caused her brother to become ill, she said.
