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 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.
Like neurotic parents, Argentines swing from criticism to unconditional love for their star footballer Lionel Messi this week, providing the soccer-mad nation's many therapists with rich material for psychoanalysis.
Brazil international Dani Alves says that his ultimate goal is to win the Champions League with his new Serie A club Juventus.
Lionel Messi will bid to gild his legacy as the greatest footballer of his generation here Sunday by ending Argentina's 23-year wait for a major title in a dream final against holders Chile in the Copa America Centenario.
Barcelona are not contemplating selling their Brazil forward Neymar, the Spanish champions' financial vice-president Susana Monje said on Wednesday.
Barcelona defender Gerard Pique insists he was merely crossing his fingers after being accused of raising his middle finger during the Spanish national anthem before his country's Euro 2016 game against Croatia.
Andres Iniesta reveals he wanted to take the penalty that Sergio Ramos missed in Spain's 2-1 Euro 2016 loss to Croatia on Tuesday.
Barcelona agree to pay a fine of 5.5 million euros to the Spanish authorities to settle a tax fraud case over the transfer of Brazil international Neymar in 2013.
Lionel Messi scores a breathtaking second-half hat trick upon his return as Argentina qualify for the Copa America Centenario quarterfinals courtesy of a 5-0 demolition of 10-man Panama in Group D on Friday.
