Christina Aguilera is Sia's new best friend

Bisexual singer Sia has been working on her follow-up to Some People Have Real Problems, and this time around, she's bringing in the big guns.

Sia is collaborating with Christina Aguilera on new tracks for the unnamed CD, which Sia wrote about on her blog this week. But it's not just music they're working on — it's a newfound friendship that includes "Super Mario," Apples to Apples and a game of pool (Christina won).

However, Sia does claim to have been victorious in Scrabble:

i can never be a better singer than her,but i sure can hope to get the word 'hexagons' on a triple word score,you feel me?

On Christina's talent, she writes:

i definitely pooped my pants when she first sang out loud in the room with us. little prickles stood up all over me,and marched first up,then down,then up again. when i heard 'beautiful' in david's car for the first time,i remember thinking,this is the best song i can remember hearing maybe ever,who is it? it didn't surprise me at all when he said 'christina aguilera',but it does surprise me that just a few years later,i find myself collaborating with the voice that brought that song to life.

But it's not just her singing that Sia appreciates: She goes on to write that Christina Aguilera is "a nice person, a good person, an awesome mama, an incredible talent, incredibly professional, a feminist and a rad role model for women who want to believe we can have it all, do it all."

Considering I do not know Ms. Aguilera personally, I will have to take Sia's word for it. I'm sure there are plenty of people who might find her degree of feminism arguable, but nonetheless, she does seem to have a staying power in the music business — and good taste in Australian songwriters she's working with.

And the ultimate reason why, with Sia and Christina working on four tracks together for Sia's new album, it is sure to be a hit?

and we share the same birthday which means, according to the playground rules i like to live by, xtina and i are in grade 1 at school,and she is my new best friend.

I can't wait to hear what comes from these women with distinctive voices and styles. Are you interested in hearing what comes of their playdates?