Offer made

Hi all. I have made an offer on an item prior to the auction closing. It has subsequently closed and the seller has made a fixed price off, I assume to all watchers. The amount of my offer and the fixed price offer differ.
Can I assume that now that there has been a fixed price offer made, that my "contracted" offer has effectively been cancelled and is really null and void? Love to hear a definitive answer so that I know how to proceed :)

Ric