Spezia placed 15th in Serie A last season and appointed former Italy midfielder Thiago Motta as coach this month.
Lukaku, who scored four goals in four games, is the only one of the six top scorers at Euro 2020 included in the lineup.
At his first news conference as Roma coach on Thursday, Mourinho's steely determination and prickly nature resurfaced when questioned about his apparent slide away from the coaching elite.
Despite the heat they thronged outside the city's Ciampino airport to greet the self-declared 'Special One' with a party atmosphere and flares heralding in the new era.
In a statement Fiorentina said that Italiano, who last season managed Spezia, has signed a deal until June 2023 with the 'Viola' with an option for an additional year.
The 23-year-old English player arrived last January on loan with the club exercising their option to buy for a reported 28 million euro ($33.4 million).
Young, who turns 36 next month, completed a free move to Villa where he played for four years before leaving to join Manchester United a decade ago.
Gennaro Gattuso was named coach of Fiorentina on Tuesday, two days after his final game with Napoli.
The former midfielder, who enjoyed trophy-laden spells as a player at AC Milan and Juve, led the Turin giants to the Italian Cup and Italian Super Cup titles in his brief reign.
Conte had openly contemplating leaving Inter a year ago when he severely criticized the club's Chinese owners for failing to "protect" the squad from criticism.
Two penalties from Franck Kessie helped Milan to a 2-0 win at Atalanta, which had already claimed a top-four spot along with Serie A champion Inter Milan.
Juve's nine-year title run was ended by Inter Milan and failure to qualify for the Champions League would be a financial blow.
Former Italy captain Buffon is an iconic figure in Italian football, one of the stars of the Azzurri's 2006 World Cup triumph who racked up a record 176 caps for his country.
While AC Milan and Inter Milan backed out of the ill-fated bid to form a breakaway competition, Juventus remains the lone holdout in Italy.
The match in Turin was a direct fight for a top four finish, with both Milan and Juve locked on the same number of points.