Struggling Napoli sacked Walter Mazzarri on Monday and brought in Slovakia coach Francesco Calzona just two days before hosting Barcelona in the Champions League.
The 62-year-old Mazzarri became the second man to be sent packing this season by the ailing Italian champions.
Mazzarri took charge in November after Rudi Garcia was dismissed but Napoli then fell to ninth in Serie A ahead of Wednesday's last 16, first leg with barca at the Stadio Diego Armando Maradona.
"I thank Walter Mazzarri, a friend of the De Laurentiis family and Napoli, for having helped the team in a tricky period," said Napoli owner Aurelio De Laurentiis on X, formerly Twitter.
De Laurentiis confirmed that Calzona has been hired, reportedly until the end of the season, and will be in charge on Wednesday night.
"It's always painful to sack a friend," said De Laurentiis in a short interview with Sky Sport.
"But we need to consider that in Naples you have to give Napoli fans something extra. Now we're going to try to do that with Francesco Calzona."
Calzona guided Slovakia to Euro 2024 but has a huge job on his hands as he returns to Napoli, where he was an assistant under Maurizio Sarri and during Luciano Spalletti's trophy-less first season with the club.
The 55-year-old will reportedly keep his job with Slovakia while also trying to drag Napoli back up the table after the disappointing end to Mazzarri's brief second spell in charge of southern Italy's biggest club.
Mazzarri helped return Napoli to the upper echelons of Italian football between 2009 and 2013.
He guided Napoli to the 2012 Italian Cup, beating undefeated league champions Juventus in the final to win the club's first trophy in over two decades.
Mazzarri left in May 2013 after finishing second in Italy's top flight with a thrilling team which boasted Ezequiel Lavezzi, Marek Hamsik and Edinson Cavani in attack.
He had a much less impressive three months this time around however, failing to get anything out of a team which romped to a historic third Scudetto last season.
Since title-winning coach Spalletti stepped down in the close season, chaos has reigned in Naples.
Napoli are a whopping 27 points behind league leaders Inter Milan after winning just four of 12 league matches since Mazzarri took over, collecting 15 points.
That is even less than the 21 that Garcia managed from his 12 league matches in charge, a total that had Napoli fourth when the Frenchman was dismissed.
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The chances of Napoli getting back into and next season's revamped Champions League are exceedingly slim, even if Italy wins a fifth spot.
Napoli are nine points behind both fourth-placed Atalanta and Bologna in fifth, and have shown little sign of being able to claw back that gap, failing to score in nine of Mazzarri's matches in all competitions.
After Barcelona, Calzona will have a relatively simple debut in Serie A, with fixtures against relegation-threatened Cagliari and Sassuolo.
