The power to fly: you could be like Superman without the superhuman strength. You could smash all overheads and you'd never get lobbed. Drawbacks: your reaction time would not change so the power of flight will not give you quicker reflexes, just the flight itself. Superhuman speed: you could be like the Flash. You can chase down any ball and change directions on a dime. Drawbacks: you need to control your new found speed so if you swing too fast without control, the balls will go long. You will not be able to fly. Which power would you pick and which power could help you beat Roger Federer?