Zeroboxer by Fonda Lee
Published by Flux, April 2015
Publisher's description: A rising star in the weightless combat sport of zeroboxing, Carr “the Raptor” Luka dreams of winning the championship title. Recognizing his talent, the Zero Gravity Fighting Association assigns Risha, an ambitious and beautiful Martian colonist, to be his brandhelm—a personal marketing strategist. It isn’t long before she’s made Carr into a popular celebrity and stolen his heart along the way.
As his fame grows, Carr becomes an inspirational hero on Earth, a once-great planet that’s fallen into the shadow of its more prosperous colonies. But when Carr discovers a far-reaching criminal scheme, he becomes the keeper of a devastating secret. Not only will his choices place everything he cares about in jeopardy, but they may also spill the violence from the sports arena into the solar system.