City handed a debut to Scotland international Ross McCormack following his arrival on loan from Aston Villa, but it was Kamau who stole the show at AAMI Park.
The winger broke the deadlock just before half-time, coolly slotting in from the edge of the penalty area after Brisbane could only partially clear a corner.
McCormack played a significant role in Kamau’s second, picking out Nick Fitzgerald on the left, with Kamau turning in the eventual cross with the help of a deflection to wrap things up 16 minutes from time.
