They recruited experienced midfielder Ikay Gundogan, who captained Manchester City to the Premier League, FA Cup and Champions League treble last season, ending a successful seven-year stint in England during which he won 12 major trophies.
Gundogan will help mentor a young Barca squad as they try to retain the LaLiga crown and get back to winning ways in the Champions League after years of European disappointments.
They exited at the group stage of Europe's top club competition for the second year in a row last season and were knocked out of the Europa League by Manchester United.
Barcelona have won the Champions League five times, most recently in 2015, and face a tough task to get back to the top table of European football after being forced to sell club legend Lionel Messi due to financial problems.
Their outstanding domestic campaign was somewhat overshadowed by turmoil off the pitch including deepening financial issues and a refereeing scandal that could drag on for years.
Spanish prosecutors in March filed a complaint over alleged payments Barcelona made from 2001 to 2018 totalling 7.3 million euros to firms owned by former refereeing official Jose Maria Enriquez Negreira.
A Barcelona court has agreed to take on the case and UEFA has provisionally cleared the club to compete in this season's Champions League despite ongoing investigations.
They will not be able to play at their beloved Camp Nou for the next few seasons as they have agreed a financing deal worth 1.45 billion euros to renovate the iconic but outdated stadium.
The 100,000-seater Camp Nou was the club's biggest source of income and they will be forced to be creative to stay competitive within the restrictions of LaLiga's Financial Fair Play (FFP) rules.
Gundogan's arrival, Lewandowski's consistency, reliable goalkeeper Marc-Andre ter Stegen and young players like Pedri, Gavi, Ronald Araujo, Luuk De Jong and Jules Kounde give Xavi a plenty of reasons to be optimistic.
But he suffered a big blow last week with news of the imminent departure of French winger Ousmane Dembele who is joining Paris St Germain.
Barcelona begin their LaLiga defence on Sunday in the Spanish capital against Getafe and although the fans are still celebrating last season's romp to the title, there is plenty for them to be concerned about
