Italian champions Napoli appointed former manager Walter Mazzarri as their new coach, the Serie A club said on Tuesday.
The 62-year-old takes over from Rudi Garcia after defeat by Empoli left last season's champions on 21 points, 10 behind leaders Inter Milan in the standings.
Napoli have lost three of their opening 12 league games, the other defeats coming at home by Lazio and Fiorentina, and - having drawn another three - sit fourth, two points behind third-placed AC Milan and eight adrift of Juventus in second.
The lacklustre start to the season reached a crescendo on Sunday when Napoli lost 1-0 at home to Empoli as Garcia's tactics failed to produce a result against the team currently 17th in the standings.
Garcia took charge at Napoli in June after Luciano Spalletti resigned having won Napoli's first Scudetto since 1990, but they are now at risk of falling away in this season's title race.
At the same stage last term Napoli were unbeaten in Serie A, leading with 10 wins and two draws.
Mazzarri returns to Napoli for a second spell after he managed the team from 2009-2013.
He ended his debut season 2009-10 in sixth place before he helped Napoli qualify for the group stage of the Champions League the following campaign.