The El Madrigal stadium holds only 17,000 - Celtic are only officially entitled to 1,600 tickets for the game. Today's newspapers are reporting that Celtic will negotiate 4,000 tickets, as Villarreal fans struggle to fill their stadium.
It was originally thought that tickets would be impossible to come by for the game, but with Villarreal set to give Celtic a fairly decent allocation, as well as the fact that many Celtic fans now live on the Costa Blanca, it doesn't seem as dim as first expected.
There is also a Spainsh website selling tickets for the game, their link is shown below.
http://www.madrid-tickets.net
You can talk about this topic on the Celtic-Mad Messageboard.
http://boards.footymad.net/mboard/load.php?tno=246