It is always better to root for someone than to root against someone. What you really hope for is your team’s success, not the opponent’s failure, even though the latter is a necessary consequence of the former. (An even better attitude would be to hope that the best team may win, but for many sports fans that’s too much to ask.) In any case, your question applies to healthy, friendly competition on the playing field. In that realm, as you’re perched on the edge of your seat lauding or lamenting, it’s okay to wish that every play go your way. It would be a sin to cheat or sabotage the game to put your team at an advantage. But just cheering for the outcome you desire is fine. And when the game is over, be gracious, set aside any negativity and wish the opposing team better luck next time or congratulations if they have beaten your team.