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.
Barcelona president Josep Maria Bartomeu predicts that Lionel Messi would not only extend his contract with the Catalan club but also end his playing days there too.
Lionel Messi announced a press boycott to protest against a journalist who alleged team-mate Ezequiel Lavezzi had used marijuana at Argentina's training base.
European Golden Shoe winner Luis Suarez said negotiations to extend his contract with Barcelona until 2021 were running smoothly.
Stars of Emmy-winning television epic "Game of Thrones" got a front row seat at the Lionel Messi show on Sunday as the Argentine superstar scored his 500th Barcelona goal.
After beating the 'best team in the world', playing lowly Middlesbrough on a November afternoon in the north of England should bring Premier League leaders Manchester City nicely back to earth.
Barcelona will put Manchester City to the sword if they commit the same kind of errors as they did in their Champions League encounter last month, coach Luis Enrique has said.
Barcelona centre-back Jeremy Mathieu joined the club's mounting injury list and faces three weeks out after hurting his right calf,
Barcelona's Uruguayan star Luis Suarez on Thursday collected the Golden Shoe award for the leading scorer in Europe last season
Barcelona defender Javier Mascherano extended his contract with the Catalan giants until 2019 on Monday.
Argentina's pain is Barcelona's gain as Lionel Messi returns for the Spanish champions when Deportivo la Coruna visit the Camp Nou on Saturday after being sidelined for three weeks with a groin injury.