Iggy Azalea says Rita Ora always "gets the party started".

The two popstars have become firm friends and collaborated on track Black Widow for Iggy's album The New Classic. They work well together but play even harder.

“Rita’s a superstar and she will only get bigger,” Iggy grinned to British newspaper Daily Star. “She’s one of those girls that always gets the party started, she is so mischievous, it’s great going out with her."

Black Widow was actually written by 29-year-old superstar Katy Perry. When the Firework singer said she couldn't fit singing the track into her schedule, Iggy, 23, knew she had to find someone equally as talented.

“The sky’s the limit for Rita," she gushed.

“Katy couldn’t get time to sing on the track herself, so we wondered who else could do it. It needed someone who could really sing, as Katy’s voice is awesome. Rita is a great fit. Her voice can blow people away.”

It's not just Katy and Rita, 23, who helped make the album work. The New Classic also features collaborations with T.I. and Mavado, but Iggy was initially wary of teaming up with other stars.

“I changed my mind when Katy said she kept thinking of me when she wrote Black Widow, but it was months before I got to hear the song," she revealed.

“I was going: ‘Play me the damned song! What the hell?’”

The blonde star is currently in the midst of The New Classic Tour, which moves through the US and Canada. She supported Beyoncé Knowles on her The Mrs. Carter Show World Tour and working alongside the star helped the Australian-born singer realise what she could go on to achieve.

“Opening for Beyoncé made me realise what can happen on stage if I get the same number of fans," she smiled.

“I’d love to be able to have sets that are two storeys high, with me flying across the stage on wires and doing magic tricks like Katy Perry does.”