Chris Brown partied with his ex-girlfriend Karrueche Tran on Friday night (03.05.13).

The 'Fine China' singer - whose on/off girlfriend Rihanna is currently on her 'Diamonds World Tour' on the east coast of the U.S. - was spotted enjoying a night out with the model and fashion designer at Emerson nightclub in Los Angeles ahead of his 24th birthday on Sunday (05.05.13).

A source told HollywoodLife.com that Chris and Karrueche are ''cool friends'' and Rihanna is okay with them hanging out from time to time.

The insider added that he and the 25-year-old 'Stay' singer are ''into each other way too f**king much'' to let his friendship with Karrueche come between them.

Chris, who is still on probation for violently beating Rihanna in 2009, previously revealed he would always have a soft spot for his former flame - who was recently said to have moved on with NBA star John Wall - because she supported him during the worst time in his life.

He said: ''She was my friend through it all. It was a friendship more than a relationship. I still love her, but at the end of the day, it's like I got love for her. She gone always be my homie!''

He also said he wishes ''all the best to her. We still have a clothing line. I only want her to progress. I don't want to stop her blessings.''

Chris is set to host a huge birthday bash in 1 Oak nightclub in Las Vegas tonight (04.05.13) and is trying to convince Rihanna to join him for the night after she was forced to postpone her concert in Brooklyn, New York on Sunday because the Brooklyn Nets need the venue to compete in the playoffs.

A source said: ''That's his number one and he wishes she could be with him on his birthday just like he was with her.

''But that's just how it goes sometime. They can't be together every second.''