 Complete the following phrase:  Nicknamed lAbatino, and the Golden Boy of Italian football throughout his career, Rivera was the product of his hometown clubs youth football academy; he joined the first team in 1958 and made his debut in Serie A for the Alessandria senior side against Internazionale on 2 June 1959 at the age of only fifteen years, nine months and fifteen days, in a 11 draw; later that year, he scored his first Serie A goal in a 22 home draw with Sampdoria on 25 October. He is the third youngest player in history to debut in Serie A, behind only Amedeo Amadei and Pietro Pellegri, and the second youngest goalscorer in Serie A, behind only Amadei. A year later, he was bought by AC Milan on a co-ownership deal, as an eventual replacement for the clubs captain Juan Schiaffino in the playmaking role; although the clubs officials were concerned about Riveras diminutive physique during his trial, Schiaffino insisted that the talented youngster be offered a contract, and later served as a mentor to the young attacking midfielder. Rivera spent his 