$re = '/^first(?:\s+(?ufsuj33004\b)\w+)*\s+last$/im';
$str = 'First one two word last
first three ufsuj33004 four last
first five swordfish six seven last';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php