The 62-year-old Mazzarri became the second man to be sent packing this season by the ailing Italian champions.
Girona defeated their Catalan rivals for the first time ever in the top flight in a pulsating battle to rise two points above Real Madrid, second, after their 1-1 draw at Real Betis on Saturday.
Champions Barca were dominating the match early on under the scorching heat of south Madrid, with Brazil winger Raphinha the main threat to the home side's defence by running the right channel and creating several opportunities.
Barca's friendly against Juventus, due to be played later on Saturday, was cancelled after an outbreak of viral gastroenteritis among the Spanish team
Xavi's side wrapped up the title after two first-half goals from Robert Lewandowski spurred them to a 4-2 win against city rivals Espanyol on Sunday
UEFA opened a formal investigation into Barcelona last month for potential violation of the European soccer governing body's legal framework regarding payments made by the club to a company owned by a senior refereeing official
Barcelona beat Real Madrid 1-0 in the Copa del Rey semi-final first leg on Thursday at the Santiago Bernabeu, but were criticised for only having 34 percent possession
Fernandes told BT Sport. "The belief of the fans, they push us through difficult moments. We have made great comebacks, the club is made also by that. In the past we have done a lot like this result"
Mexico's Pumas on Saturday signed Dani Alves after the veteran Brazilian defender left Barcelona for a second time.
Neymar highlights the importance of Lionel Messi at Barcelona while hinting that he wants compatriot Gabriel Jesus to join the Catalan giants.
Barcelona return record revenues of €679million during 2015-16, according to the club's financial results for the season.
La Pulga Atomica of Barcelona, Lionel Messi and his teammates are put through their paces at England's St George's Park training base on Monday for their pre-season friendly.
Barcelona star Lionel Messi reportedly cancels plans to travel to Turkey following a military coup d'etat in the country.
Barcelona vow to support Lionel Messi following his decision to appeal against the 21-month jail sentence handed down to him by a Spanish court after being found guilty of fiscal fraud and believe the verdict is "an attack on his person".
The EU on Monday orders seven Spanish football clubs including Barcelona and Real Madrid to pay back millions of euros (dollars) in illegal state aid.
Neymar will stay with Barcelona after signing a five-year contract, the club have announced.
World Cup winner and Brazil legend Ronaldo feels "abandoned" by Lionel Messi and hopes he reneges on his retirement from international football.
Lionel Messi's retirement from the Argentina national team has turned the country upside down in the past few days, with an entire nation stunned by the news after Chile beat them in the Copa America final.
It seems like a curse. There just aren't many footballing reasons to explain Argentina's latest failure in the Copa America Centenario final against Chile.