Wiktionary
there's only one
phr. (context idiomatic English) Used in a chant, most often in sports matches, to express support for an athlete, coach, team etc..''
Usage examples of "there's only one".
If I take Preston Bay first they'll know what I intend because there's only one thing a sane man could do from there.
So if you want to really be able to predict the future -- not in everything, but in some areas -- there's only one regime of human scholarship, of human claims to knowledge, that really delivers the goods, and that's science.
Man got him into this - there's only one way man can get him out of it.