Rapper Dragon has become the first horse to complete the Classic series for four-year-olds with his victory in the Hong Kong Derby.

The former Sydneysider added Sunday's Derby (2000m) to his wins in the Hong Kong Classic Mile (1600m) and Hong Kong Classic Cup (1800m) when he held off Pakistan Star.

It was champion jockey Joao Moreira's first win in the Derby and trainer John Moore's sixth.

Known as Street Rapper when trained by Gai Waterhouse, he was runner-up to Takedown in a Group Three race and second again to Pasadena Girl in the 2015 Group One Champagne Stakes at his last Australian start.

"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.

Moore said Rapper Dragon's options included the QEII Cup (2000m) and the Champions Mile which was his preferred option.

"We're going to toss up between the Champions Mile and the QEII," he said.

"I want to dodge Werther though. Rapper Dragon's got versatility so I'm sure I can freshen him up and bring him back to the mile."