The 3-3-1-3 is not an entirely new concept, though it has become more popular in recent years due to its dynamic attacking nature. In particular, Chile National Team coach Marcelo Bielsa and current Bayern Munich coach Pep Guardiola have implemented this system with great success. This book explores, in detail, the strengths and weaknesses of the system, the roles and responsibilities of each player in both attack and defense and the permutations of the team shape against different formations and in varying situations. Depending on the circumstances at any one moment of the match in terms of the score, the opponent's tactics, time remaining etc., the formation could become a 1-3-4-3, a 1-2-3-2-3, or even a 1-5-4-1 in an ultimate defensive setup. This adaptability, the FLEX, is made possible by teaching players to recognize the rotations required "on the fly" by presenting them with very specific game situations in training. In this book, Harrison takes you through his training sessions geared toward developing in players the tactical and spatial awareness necessary to run the FLEX 1-3-3-1-3 successfully.