It's by Gregg Easterbrook, another Atlantic colleague. I like its ecumenism:
God (or Adonai or Allah), let me play well but fairly.
Let competition make me strong but never hostile.
In this and in all things, guide me to the virtuous path.
If I know victory, grant me happiness;
If I am denied, keep me from envy.
See me not when I am cheered, but when I bend to help my opponent up.
Seal it in my heart that everyone who takes the field with me becomes my brother.
Remind me that sports are just games.
Teach me something that will matter once the games are over.
And if through athletics I set an example let it be a good one.
(Photo of Welsh rugby team before their game with Ireland last week by Stu Forster of Getty. In Wales, rugby is a religion, so this prayer seemed appropriate.)