Former Inter Milan coach Luigi Simoni, who led the club to the UEFA Cup title in 1998, died in Pisa on Friday at the age of 81 years.
Simoni, whose coaching career spanned four decades, never recovered after suffering from a stroke almost a year ago.
"Today, 22 May, he left us. Not just any date, the most Inter-related date of all," Inter Milan said in a statement.
Inter on Friday marked the 10th anniversary of becoming the first Italian team to win the treble, when the Jose Mourinho-led side won the Champions League final.
"A great football man has left us," said Italian football federation president Gabriele Gravina in tribute to Simoni.
A midfielder during his playing career Simoni lined out 368 times, including 187 in Serie A, scoring 32 goals for clubs including Juventus, Torino and Napoli, with whom he won the Italian Cup in 1962.
He started his coaching career at former club Genoa in 1974, guiding them to Serie A the following season, the first of eight promotions achieved for his teams.
He was most remembered for his time with Inter Milan, joining along with Brazilian star Ronaldo in 1997, and lifting the UEFA Cup the following year after beating Lazio in the all-Italian finals.
They missed out on the Serie A title that season, finishing second to Juventus.
"He arrived in the Nerazzurri dugout in 1997, together with El Fenomeno, Ronaldo," Inter Milan recalled.
"That combination, Simoni-Ronaldo, will remain in everyone's hearts forever, and not just those of Inter fans.
"That was a father-son relationship, one in which he showed great compassion towards a truly special footballer: Simoni loved to tell us, 'I learned more from him than he did from me that season.' A phrase that brilliantly encapsulates what type of person he was."