如何使用php preg_match来获取日期

Trying to just grab the date in this url

upload/Standard Project/test/04-12-2011/1.jpg

the url will change names and so will the date, but it will always be in the same format.

Any idea of how would be great. I tried to date it using substr but realized that wont work because the url can change.

<?php
$str = 'upload/Standard Project/test/04-12-2011/1.jpg';
if(preg_match('@/([0-9]{2}-[0-9]{2}-[0-9]{4})/@', $str, $matches))
  var_dump($matches[1]);