Barcelona and Osasuna appealed against the decision to play the game on Thursday after it was initially postponed on March 8 following the death of a doctor at the Catalan club, but their pleas were ignored.
Barcelona were 4-2 down towards the end of the match before goals from Robert Lewandowski, Eric Garcia and Raphinha secured their comeback.
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
Spanish champions Barcelona's scheduled friendly against Saudi Arabian side Al-Ahli Saudi in Doha, Qatar, has been cancelled by the club's Qatari sponsors just six days before the game was due to take place.
Neymar says sitting out of the Copa America is worth it for the chance to lead Brazil to gold in front of a home crowd at the Rio Olympics in August.
Defender Gerard Pique praised Barcelona's resilience after they ended an emotion-filled season by clinching top spot in La Liga with a 3-0 victory at Granada on Saturday.
So it all comes down to this. With just one round remaining in La Liga, a single point separates Barcelona and Real Madrid at the top of the table. Everything will be decided on a spectacular Saturday evening - and the build-up in Spain is already intense.
Barcelona will play friendlies against newly-crowned English Premier League champions Leicester and Liverpool in August, the Spanish giants announced Monday.
Real Madrid and Atletico Madrid's passage to the Champions League final and Sevilla qualifying for the Europa League equivalent for a third straight year has underlined Spain's dominance of European soccer.
Luis Enrique has lauded Lionel Messi as Barcelona's leader and "the best wherever he plays".
Brazil legend Ronaldo believes Neymar has what it takes to match Lionel Messi and become the Argentine's heir at Barcelona.
Having lead Barcelona to a record 31-match unbeaten run since last October, Lionel Messi could now very well be the driving force to lead his team to domestic and continental glory once again.
Enjoy Barcelona icon Messi putting on a show for Italian pop star Eros Ramazzotti, with an awesome trick from behind the goal.
