Barca don't need to have the same performance of last season,if not they might not be able to win the next champions league. Barca needs to improve in their performance so that they can be hopeful to win UCL. The champions league is a competition that brings the best clubs from different leagues to play amongst themselves and more is expected from most clubs. Winning your local league hasn't given you a guarantee that with the same performance you will win a competition played by the best clubs in Europe. I still believed that with the little change in the players Barca will do perfectly well in the champions league this season. As they will want people to believe in them by impressing their fans with good results.
Xavi has prepared the team to bring Barcelona to compete with other big clubs from different leagues, this time the toughest competition will come from the premier league team, Manchester City, Arsenal and Manchester United are the three teams that will give their best performances to survive in this competition. Newcastle also cannot be underestimated, Newcastle's performance last season was very good, they managed to outperform other teams such as Liverpool and Tottenham to secure a ticket to the Champions League.
Barcelona appeared in the UCL this season as the La Liga champions, they must perform optimally in order to maintain the chances of achieving their goal of winning the Champions League this season.
That Xavi Hernandez and Barcelona team has potential to win the League games but not enough to make them win the Champions League. They had the best defense last season, seeing the recent signings they will go far than we expect.
Arsenal has proper depth now they lacked that last season, and another club to keep an eye on is Manchester City they have all it takes to win the Champions League again. Barcelona will not be able the win the Champions League not this season.