Atalanta midfielder Andrea Rinaldi died on Monday at age 19 after suffering a brain aneurysm at home three days ago.
Rinaldi was part of Atalanta's youth system and had been on loan at Serie D side Legnano this season.
Legnano, who confirmed Rinaldi's cause of death in a statement, called it "a sudden and shocking tragedy, even impossible to imagine."
Rinaldi joined Atalanta at age 13 and helped the club's Under-17s win the Scudetto and Supercoppa Italiana. He had been a key member of Legnano this season and scored one goal in 23 appearances.