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.
Lionel Messi's third goal from a free-kick in as many games this year secured Barcelona's place in the quarter-finals of the Copa del Rey as the holders beat Athletic Bilbao 3-1 to edge through 4-3 on aggregate on Wednesday.
Turkey international Arda Turan scored a hat-trick as holders Barcelona thrashed third-division side Hercules 7-0 in the second leg of their Copa del Rey last-32 tie.
Barcelona coach Luis Enrique says Neymar's performances remain at their peak, despite the Brazilian's flagging goal tally this season.
Barcelona star Lionel Messi should win the Ballon d'Or award every year, according to club president Josep Maria Bartomeu, after the Argentine was beaten to the prize by Real Madrid rival Cristiano Ronaldo.
Barcelona have agreed to withdraw an appeal against fines imposed by UEFA last year after their supporters waved pro-Catalan independence flags at two matches, European soccer's governing body said on Monday.
Luis Suarez celebrates his bumper new five-year Barcelona deal in style with a double as the champions defeated Espanyol 4-1 in the Catalan derby to move to within three points of La Liga leaders Real Madrid.
Luis Suarez on Friday said he was delighted after signing his lucrative contract extension at Barcelona through to June 2021.
A six-year-old Afghan boy, who shot to Internet fame by sporting a Lionel Messi shirt made out of a plastic bag, fulfills his dreams by meeting the Argentine soccer great.
Real Madrid remain six points clear at the top of La Liga after Sergio Ramos's late leveller earned a 1-1 draw at Barcelona in El Clasico on a weekend in which none of the top six won.
Real Madrid captain Sergio Ramos rescued a draw and maintained the European champions' six-point lead at the top of La Liga in a 1-1 draw at Barcelona on Saturday.