Hulk VS Rhino in a headbutt fest

You know the drill. Rhino and Hulk are headbutting each other forehead against forehead. who goes down first and who wins

Rhino was surprised that his horn was able to penetrate Grey Hulk's skin from a full on charge once. Stronger incarnations might result in Rhino getting his neck broken trying the same thing

Might, but we don't know for sure. Remember the Serpent Tooth, gundam.

Hulk