The divorced couple were both in attendance at the NBA season opener for the Los Angeles Lakers Vs. the Dallas Mavericks at the Staples Center in LA.
Katy took her Dad, Keith Hudson, to check on the action and the pair were seated on a different side of the arena from Russell, who cheered on and enjoyed the game.
On his respected side of the arena, Russell Brand chit-chatted with a young friend and sent out a few text messages on his phone.
While the former lovers didn't interact, the crowd was star studded and those celebs chatted with each other. David Beckham and Adam Levine sat next to each other and shared in some jokes while Floyd Money Mayweather repped the money team while devouring a hot dog.
Despite the star-studded audience, the Lakers lost a close a close game with a final score 99-91.
Check out all the stars in the gallery above!