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
Lionel Messi's father says he could never have dreamed of the success Barcelona's five-time Ballon d'Or winner has enjoyed.
Culprits write 'Messi' on the back of the bronze homage to the Portugal international Cristiano Ronaldo, scribbling the number 10 underneath.
Lionel Messi is rewriting football history. Before the emergence of the Argentine attacker just over a decade ago, the game's records were spread out among a select band of legends. But now there are hardly any left for anyone else.
Barcelona midfielder Arda Turan believes superstar forward Lionel Messi is "a miracle from God".
The Spanish Sports Press Association "demands a public retraction" of the statement made by Barcelona player Dani Alves where he branded the Spanish press as "f****** rubbish" on social media.
Espanyol goalkeeper Pau Lopez insists he did not deliberately attempt to injure Lionel Messi during his side's defeat to Barcelona.
Barcelona open up a comfortable lead in their Copa del Rey last-16 clash with Espanyol after winning the first leg 4-1 at Camp Nou.
Javier Mascherano has won 16 major trophies in his career, but he still couldn't avoid being nutmegged by Lionel Messi during training in an open session.
Barcelona finish 2015 as the most prolific outfit across Europe's top five leagues led by their ferocious 'MSN' attack of Messi, Neymar and Suarez.
Four-time World Player of the Year Lionel Messi has warned Barcelona's rivals that the European champions are determined to match their five-trophy haul from 2015 in the coming year.
