This is a theoretical book about a chess variation that (it could not be otherwise) I will call the Del Rio Variation. It is one of the most fascinating openings that can be played today, leading almost immediately to highly dynamic and complex positions. Additionally, it can be set up quite easily. For example, after 1.d4 Nf6 (1...d5 is another possible move order to reach the same position) 2.c4 e6 3.Nf3 d5 4.Nc3 (from 1.d4 all of White’s moves are the most popular). Then 4...dxc4, establishing the Vienna Variation. Here, White can only fight for an advantage with 5.e4.

Until a few years ago, the main lines continued with 5...Bb4 6.Bg5 c5, or the dangerous gambit 6.Bc4!? Nxe4 7.0-0.

All of these led to a well-researched ocean of variations where Black had to struggle to maintain equality and generally had few practical chances to win the game. The scenario changes dramatically with 5...b5!? as Black now sets up a complicated, unbalanced game that is also less studied than the other continuations. This partly explains the excellent results that Black has been achieving in practice. It is no surprise that this move has attracted the interest of today's top players, some of whom have adopted it frequently.

This book is especially focused on Black's perspective and aims to provide you with all the necessary material to successfully employ this variation. You will find theory, exemplary games, deep analyses, conceptual explanations, and many novel ideas that have yet to see the light of day in practice