Controller and username with same slug


I want to do a profile page for evey user in muy social network, for example But I want do a shorthand url for every profile with an alias (like

I guess that I have to change the url manager to solve this and when access to open the desidered profile page.

My question is, imagine that I have a controller named "user", and a user choose for their alias the word "user". If access to that opens the profile or the controller?

I think is relative to the rule order in the url manager. In that case I must to use forbidden words or something?

Thanks and sorry for my english, I hope you understand more or less.

it depends on rules order in config - first match wins.