Beauty Generation’s reign as the best horse in Hong Kong looks to be over after the superstar had his colours lowered for a second race in a row, upstaged by Waikuku in the Group Two Jockey Club Mile.

After looking bulletproof for 18 months, the seven-year-old is mortal again.

On the back of 10 straight wins, John Moore’s two-time Horse of the Year suffered his first defeat in the Group Two Sha Tin Trophy last month but there were excuses – the handicap conditions and a hard first-up run, while he resented being caught inside other horses.

The assumption was the real Beauty Generation would stand up on Sunday with more favourable circumstances and a bit of a freshen up – that’s why he started at $1.30.

Unfortunately for his legion of fans around the world, it wasn’t the case.

Jockey Zac Purton was determined to take luck out of the equation, pushing hard from the start and angling out from barrier one.

The tactic ensured Beauty Generation wouldn’t be boxed in and if noted front-runner Ka Ying Star wanted to keep rolling, Karis Teetan would have to work for it.

But even from in front things seemed slightly off – he wasn’t running his typically brutal sectionals during the middle stages – and there was no kick at the top of the straight.

Tony Millard warns Beauty Generation can go from champion to has-been overnight ahead of Jockey Club Mile clash

Instead, it was the John Size-trained Waikuku, who enjoyed a dream run in transit under the guidance of Joao Moreira, who proved the strongest, taking the inside run and sprinting home to take the prize.

While that was a shock to the system, perhaps the biggest concern for Beauty Generation’s supporters is the fact the aforementioned Ka Ying Star was also able to get past him in the run to the line.

“Obviously we’re disappointed in his effort,” Purton said. “He’s better than that and at level weights next time, hopefully he can stand up.”

Zac Purton and John Moore discuss Beauty Generation’s effort.

Despite the “flat” run, Moore isn’t giving up hope yet and believes he can turn him around for the Hong Kong Mile.

“When he came into the straight I expected him to kick and put two [lengths] on Waikuku, but he didn’t. I’ll go back and just see what we can tweak to get him on song for the grand final. There’s two things I can tweak before the big day and we’ll have him cherry ripe,” he said. “I’m confident he can be right there, he only got beat three-quarters by [a length] still giving away five pounds. It’s not that poor a run.”

Beauty Generation suffers first defeat in 18 months: ‘he just wasn’t comfortable’

In contrast, there are no concerns about Waikuku, who has gone to another level this season after finishing runner-up in the Hong Kong Derby.

It is the second time he has beaten home Beauty Generation and he is a genuine contender in next month’s 1,600m Group One.

“He just keeps improving every day he goes to the races,” Size said. “It will be a tougher race in December, so he’ll have to improve again to win.

John Size and Joao Moreira share a laugh after Waikuku’s win.

“He’s a typical good horse. Most of the good horses are like that – they don’t do anything wrong. That’s why they are who they are.”

Moreira admitted the result was “a good surprise” and he was able to take advantage of the situation ahead of him.

“What happened down the back straight no-one would have expected because they moved quite far away from the fence. It left my horse with plenty of space in there and he was nice and comfortable,” the Brazilian said.

Is there a new Derby favourite? Waikuku stuns rivals with Sha Tin blitz

“When we were turning for home, Ka Ying Star wasn’t giving any ground – he was holding me in there and I was forced to hold on and hope that the gap would come on the inside of the leader Beauty Generation.

“Once it came, my horse was full-on, he just went for it and didn’t hesitate. Good horses do it – they go through small gaps and he has proven himself.”