Use selectors to find the div and apply an alternative style, this means you won't need to apply a class to said div element.....
If the div in question is always the first div after the one with the class you would do it like so....
Code:
div.yourclass > div:first-child {color:#fff}
Of course the color was just an example as was the div class name....
Bear in mind if your div in question is sat inside another element you will need to include that in the selector, i can provide further examples if needed.
If you're ok with reading about how to use them you can find the info here..
http://www.w3.org/TR/CSS2/selector.html
As said, i don't mind providing examples...