The besties have more in common than their sexy, unconventional style, their constantly changing hair and their pulse-quickening dance moves. Katy Perry has just tied her BFF Rihanna at radio, matching her for the most No.1s on the Mainstream Top 40 chart. Perry's 'Wide Awake' just landed in the coveted No. 1 slot, marking her ninth No. 1. Wow! That's a lot of chart toppers, Katy!

What's most impressive about this achievement, other than it was made by females, is that Rihanna's career launched in 2005 and Perry's in 2008, so it took them both a relatively short period of time to rocket to the top of the chart a total of 18 times combined. The chart has been around since October 1992, making it an even more astonishing feat. It didn't take our gals long, did it?

According to Billboard, the Mainstream Top 40 chart history remains dominated by women. Lady Gaga, Pink and Britney Spears all have seven No. 1s. Beyonce and Mariah Carey are in a diva deadlock with six No. 1s a piece.

Congrats to Katy Perry for pulling alongside Rihanna with her latest sonic feat.

Now the question remains. Which diva will pull ahead and score the 10th No. 1 first? Perry looks to have closed out promotion of 'Teenage Dream' with the reissue, which included 'Wide Awake,' while Ri is still banging out jams from 'Talk That Talk.' Both are expected to work on follow up albums sooner than later.

Time to sharpen those chart-climbing claws, ladies!

Watch the Katy Perry 'Wide Awake' Video