This is a bit unusual but very welcome. In Bilbao, starting tomorrow, two major events will run concurrently - indeed, simultaneously - through Saturday, September 20: the Grand Slam Masters Final and the European Club Cup.
The first is a four player double-round robin with Levon Aronian, Viswanathan Anand, Ruslan Ponomariov and Francisco Vallejo Pons. While Anand is bound to be hiding most of his preparation it's still very important for him to show or at least reach good form in this event, to get ready for his coming world championship match with Magnus Carlsen and to keep his confidence up. (And maybe to give Carlsen some reason for concern, giving the latter's decent but not perfect form this past summer.) For Aronian too the tournament has some importance, as 2014 from the Candidates' tournament on has been very disappointing, and he has managed to drop more than 40 points from his peak earlier this year.
The second event is one of those delightful team tournaments where many if not most teammates have nothing more in common than who wrote their checks, but with so many of the world's top players involved, who cares? In fact, between the two events nine of the world's top ten is playing - only Magnus Carlsen is absent - and a large number of players from the top 50 will be involved. It's a chess feast!