UFC welterweight title?

Ok so, since Serra is injured they throw GSP in on New Year's Eve to fight Matt Hughes. Makes sense so far, but then they put the title up for grabs? Serra is still the title holder isn't he? How can they have a title fight if the title holder is injured? How is this going to work out? Does Serra have to fight the winner once he is healthy to try and get his belt back? I am pumped to see GSP vs Hughes again but this seems a bit harsh to Serra. The card overall looks awesome with Liddell against Wanderlei too. Can't wait till New Year's eve, should be awesome!