Australian bred four year-old Street Boss (USA) gelding Rapper Dragon continued his domination of the four year-old division in Hong Kong at Sha Tin on Sunday with a memorable victory in the Group I Hong Kong Derby.

Rapper Dragon (image Grant Courtney) made history teaming with Joao Moreira to win the 140th running of the HK$18 million BMW Hong Kong Derby (2000m). The John Moore-trained gelding ensured his place in the record books as the first horse to win all three legs of Hong Kong's Four-Year-Old Classic Series.

It was Moreira's first win in the race. The champion jockey, a man accustomed to breaking new ground, was elated and teary-eyed after driving the 1.8 favourite through the rain to hold off the deep-closing Pakistan Star.

"I got emotional, I was saying to everyone beforehand that it was the race I wanted to win the most and thanks to God that I achieved that," Moreira said. "I was given a 100 percent fit horse by the team – John Moore, the mafoos, the owner – and we were able to deliver, so it's a dream come true.

"The rain that fell was a little concern but it was a concern to everyone because no one knew who was going to handle the going. My horse didn't mind it; he gave his best once again and delivered the third win in the series – the big one. There isn't much else I could wish for. He's proven that he's the best four-year-old around and I'm blessed to be his jockey."

Rapper Dragon and Joao Moreira - HKJC

For Moore, Rapper Dragon's win was a sixth in Hong Kong's blue riband, the handler's tally now surpassing all others – one more than Brian Kan. 

The Australian hailed Rapper Dragon "My champion" after watching the chestnut confirm the superiority over his peers that he had shown in the Hong Kong Classic Mile (1600m) and Hong Kong Classic Cup (1800m).

"This is a really classy animal, he's done everything right, he progressed through the classes, today was the grand final and we won it. It was a great ride by the jock – it's great that the horse has got some early speed so that he could lay up on a muddling speed," Moore said after the gelding had scored by a length and three quarters in a time of 2m 02.88s.

Further Group I goals lie ahead for Rapper Dragon.

Moore is favouring a drop back in trip and a tilt at the G1 Champions Mile at Sha Tin on 7 May, although the G1 Audemars Piguet QEII Cup (2000m) one week earlier remains a possibility.

"We're going to toss-up between the Champions Mile and the QEII," he said. "I want to dodge Werther though, the way Werther's working at the moment – his work the other morning was just unbelievable. Rapper Dragon's got versatility so I'm sure I can freshen him up and bring him back to the mile – he's got the gate speed, so I'm sure he'd be a live chance in the Champions Mile."

Bred by the late Henry Cojuangco at Gooree Stud, Rapper Dragon joined the John Moore stable after beginning his career with Gai Waterhouse.

Rapper Dragon showed good ability in a five start juvenile campaign for Waterhouse that yielded a win at Wyong and seconds in the Group I ATC Champagne Stakes to Pasadena Girl and Group III ATC Schweppervescence Quality to Takedown.

Rapper Dragon has the overall record of eight wins and three placings from 16 starts.

A half-brother to stakes-placed Swing Vote, he is the best of three winners from Danehill Dancer (IRE) mare Swing Dance, a sibling to Group I winner Amanpour and stakes-winners Turf Express and Sports Edition.

Swing Dance was sold in the dispersal of Henry Cojuangco's stock at the 2015 Magic Millions National Broodmare Sale when bought by Michael Wallace Bloodstock for $360,000.

She is now at Newgate Farm, who sold her current yearling, a colt by Congrats (USA) at Magic Millions for $110,000 to KS Research.

Swing Dance produced a colt by Deep Field last spring and is now in foal to Rapper Dragon's Darley based sire Street Boss.