Competition begins on tomorrow afternoon with Desafío Español faces Alinghi in the first pairing to kick off racing in Valencia.

Will Alinghi prove as dominant in 2006 as they were in 2005? How will the new boats launched by Emirates Team New Zealand, Luna Rossa and BMW Oracle Racing square up to the might of the Swiss Defenders? Can any of the smaller teams, still sailing their older boats, pose a serious threat to the Big Four?

A total of 66 matches are scheduled over the next six days, and by the end of next Tuesday, the 12 teams will have a much better idea of how well they have spent the past six or seven months of training, boat building and testing.

One of the big dilemmas facing the bigger teams has been whether or not to put their new boats into competition.

"You either race your boat early and gain the opportunity of learning about it, or you keep your boat back and don't reveal to the others what you have", said BMW Oracle Racing skipper Chris Dickson. "But then you don't get the chance to learn about it. We have chosen to race our boat early, although racing it in the third year of a four-year campaign isn't really that early."

This is the decision that all the big three challengers have come to, each indicating they intend to race their new boats, while the Defender has decided to keep the new SUI 91 under wraps for a while longer. In any case, SUI 75 proved plenty quick enough in 2005, earning 31 victories from 33 matches.

Ed Baird, nominated as Alinghi helmsman for this Act, doesn't believe it will be anything like as easy this season. "It's unlikely that a boat that was designed four or almost five years ago should be able to outperform one of the new ones. But it's always our hope; it would be a fantastic day, if we can take a race off of a new boat."

Luna Rossa may have a better gauge of the performance of their new boat, ITA-86, than most teams because they have engaged in some informal training with the Defender.

After the travelling Acts of the past two years, when the teams visited France, Sweden and Sicily, the 2006 season marks the beginning of a new phase. From here to the America's Cup Finals just over a year from now, all racing takes place in Valencia.