Adding a class attribute to a hyperlink in Markdown

Possible Duplicate:
How do I set an HTML class attribute in Markdown?

In my original link done in plain HTML I have a class attribute like so:

<a href="http://example.com" class="noborder">my link</a>

How do I translate it to Markdown? I don't know how to put the class in.

[mylink](http://example.com)