jquery, move an inner element to the first position?

Lets say you have a list of items:

<ul id="ImportantNumbers">
   <li id="one"></li>
   <li id="two"></li>
   <li id="topNumber"></li>
   <li id="four"></li>
</ul>

Every five seconds these list items get reordered.

Using jquery whats the best way to keep #topNumber, at the top of the list during the reordering.