Mariah Carey 'cautious' Around James Packer

Mariah Carey is ''cautious'' around James Packer.

The 'Without You' hitmaker is reportedly romancing the Australian billionaire but isn't quite ready to ''let him in yet''.

A source told E! News: ''They are not talking marriage. That's ridiculous.

''She's enjoying his company, but she's also trying to remain cautious. This trip is a chance for her to really get to know him. She hasn't 100 percent let him in yet.''

Meanwhile, the 47-year-old businessman has reportedly been courting Mariah - who has four-year-old twins Monroe and Moroccan with estranged husband Nick Cannon - for a number of months.

The 45-year-old star is believed to have been treated to a number of lavish presents including a room full of flowers for her hotel suite as well as travelling to Las Vegas to support her ahead of her Mariah #1 to Infinity residency.

Meanwhile, Mariah's ex Nick previously suggested there's a possibility of the couple reuniting.

He said: ''It's one of those things, I'm a hopeless romantic too. Through this learning process, you never say never.

''To me one thing I know, that will always be the love of my life, always be my family and that's never going to change.''