Barcelona's biggest rival right now is I think Real Madrid. Barcelona have the ability to beat all the other teams in La Liga, but they have been defeated by Real Madrid time and time again. Xavi's main reason now will be to plan how to beat Real Madrid, something the club desperately needs.
The problem is that Real Madrid always looks stronger than the other teams so it won't be easy for Barcelona to make Real Madrid lose under these conditions.
Because the Real Madrid coach who already has a wealth of experience in football also has good tactics and strategies in managing his players in the team and also in matches as you have seen against Barcelona. So this is not an easy thing for Xavi to make it happen this season.