AC Milan have appointed Massimiliano Allegri as their new coach until 2012, the 42-year-old former Cagliari trainer stepping in to fill the void left by Leonardo's departure at the end of last season.
Allegri took over at Cagliari in 2008 and, after starting his first top-flight season with five consecutive defeats, led the Sardinian side to a seventh-place finish.
He won the Panchina d'Oro award as best coach in Serie A that term, but was replaced with five games remaining last season following a run of seven defeats in nine matches.
"Today is the first day. Now I will have time to think and a month available to prepare for the new season," Allegri told Milan Channel.
"Coaching Milan represents a very important point of arrival in my career. I'm part of one of the strongest clubs in the world."
Prior to joining Cagliari, Allegri had gained experience in the lower leagues with Grosseto and Sassuolo.
During an 18-year-playing career, Allegri counted Livorno, Perugia, Cagliari and Napoli among his many clubs before retiring in 2003 at Aglianese and taking up a coaching position there the following year.
Allegri is the first Milan coach who has not also played for the club since Fatih Terim's brief tenure in 2001.
Leonardo took charge of the Rossoneri following Carlo Ancelotti's departure to Chelsea last summer and led the seven-time European champions to third place in Serie A and a spot in the UEFA Champions League group stage.
The appointment of rookie Leonardo was seen by Milan fans as a cheap option as he was already on the payroll as technical director.
The arrival of Allegri rather than a big-name coach may be viewed by the same supporters as further proof owner Silvio Berlusconi has tightened spending during the economic crisis but also wants to strengthen his grip on team affairs following several clashes with Leonardo over team tactics.
Assistant coach Mauro Tassotti and youth team director Filippo Galli were also in the running for the role, with Milan deciding low-profile names with clear coaching credentials fitted their new model better.
Allegri's move to Milan took several weeks to be finalised because he was still contracted to Cagliari despite being sacked.
Club President Massimo Cellino was reluctant to let him go given his anger at the coach's last few months in charge.
"The negotiations extended for a month but luckily everything ended well," Allegri added.
"I replace Leonardo, a coach who has done a good job. Under his leadership Milan fought until the end for the scudetto and the team played very well. Therefore I receive a very important legacy."