The first step is to understand the nature of the event. If you’re not familiar with the sporting event, talk to someone who knows it. Understanding the event will help you focus on the important moments.
If it’s an indoor venue, check out whether you have access to an AC power supply, so that you could shoot uninterrupted without worrying about running out of battery power in the middle of the shoot. Also check to obtain permission to use the power supply.
If you’re shooting outdoors, an AC power supply would not likely be an option. You would then have to equip yourself with enough battery packs to cover the entire event.
If you’re familiar with the event, you would know which parts you can leave out, enabling you to save battery power.