Australian billionaire James Packer was joined by A Lister stars, including his girlfriend Mariah Carey on Tuesday as his ambitious $4.5 billion casino launched in Macau.

James Packer and Mariah Carey walked hand in hand on the red carpet at the opening of the Studio City Casino. But the American singer, who was slated to perform that night made sure she caught her boyfriend's full attention by wearing a plunging black evening gown, which puts her cleavage on display.

Others actors who walked on the red carpet are Leonardo DiCaprio, Robert De Niro, who was also joined by his actress wife Grace Hightower and director Martin Scorsese. Other guests during the night included casino co-chairman James Ho along with his wife Sharon and Chinese actress Carina Lau.

The opening of the movie themed venture was marked by the premiere of a short movie, especially created to promote the gambling hub, titled 'The Audition.' Packer reportedly spent nearly $100 million for the short ad. It was directed by Scorsese and starred by DiCaprio, De Niro and Brad Pitt.

Mariah later performed showcasing her voice with four songs, including her hit song, 'Hero.' Some of the songs were dedicated to her close friend Ratner, who directed several of her music videos but there was no song dedicated for her beau though, as per The Sydney Morning Herald.

Casino Company's chairman Rob Rankin, chief executive Rowen Craigie, strategy boss Todd Nisbet and non-executive director Helen Coonan were present that night and seated at the Crown's corporate box, watching the whole performance.

After the sumptuous dinner, DiCaprio led the charge to Pacha, he banked a booth filled with champagne and as the party went on, dozen of women surrounded him. Packer on the hand just stayed on Mariah's side.

At around 3am Leo returned to the VIP area and his last appearance on stage was when he was escorted to the toilet by three security guards.