RewriteRule that accommodates numbers and words

[John_Betong]

@busboy

The first rule below is one that I have been using for years. Now, in addition to numbers in the URL, I would like to accept a username, like so:

This is what I have been using for years. The RewriteRule redirects everything to index.php:

  RewriteEngine on
  RewriteCond %{REQUEST_FILENAME} !-f          
  RewriteCond %{REQUEST_FILENAME} !-d
  RewriteRule ^(.*)$ index.php/$1 [L] 

I think my final rule should be replaced with the following:

  RewriteRule ^(.*)$ index.php?sponsorUsername=$1 [L]

# or even more strict and prevents any directories

  RewriteRule ^(.+)$ index.php?sponsorUsername=$1 [L]