In the 1970s, when he was little more than twenty years old, he rose to prominence thanks to awards in important international piano competitions, including Busoni, Ciani, Pozzoli, Rina Sala Gallo, Cata Monti, Beethoven in Vienna, Reine Elisabeth in Brussels, Liszt-Bartók in Budapest and the Paloma O'Shea in Santander. He was the first young pianist, in Italy, to appear in recital with the complete set of Liszt's Transcendental Studies, and the youngest to record, for Ricordi, Beethoven's Sonata op. 106 Hammerklavier. He is considered a pioneer of the great piano challenges, interpreting programmes and works of rare performance, an interest that culminated in 2002, when he presented the world premiere of his piano transcription of Stravinsky's "Rite of Spring", confirming once again his extraordinary technical and interpretative skills. This interesting transcription aroused the interest of Martha Argerich, who personally invited him to the "Martha Argerich Project" in Lugano. From that moment on, his relationship with the legendary Argentinian pianist became an intense artistic collaboration. With Argerich, Rivera appeared in piano duos in the Teatro Ponchielli in Cremona, Teatro Lirico in Cagliari, Teatro Politeama in Catanzaro, Teatro Nuovo Giovanni in Udine, Piano Festivals in Pietrasanta and Ascoli Piceno, Teatro Petrarca in Arezzo until being the architect of Argerich's return to Argentina, after many years of absence, in the memorable concert of October 19 and 20, 2012, at the Teatro El Circulo in Rosario. In August 2019 they were again protagonists in the prestigious Teatro Greco in Taormina (Sicily). Rivera recorded for Ricordi of Milan the sonata op.106 "Hammerklavier" by Ludwig van Beethoven and the "Aroldo in Italia" by Hector Berlioz in the transcription for piano by Franz Liszt together with Aldo Bennici, as well as the "Première Sonate" by Pierre Boulez live, recorded in the final round of the Busoni Competition 1976. With Irco Cosentino of Buenos Aires 2 Cd's with transcriptions and paraphrases of Franz Liszt's Operas and the 12 Transcendental Studies, and 4 live CD's of the concerts with Martha Argerich in Rosario (2012). For Radio Suisse Romande he recorded the world premiere of Sonata n.2 by Guatemalan composer Rodrigo Asturias. He has also recorded for RAI, RTSI and Cologne Radio. Very active as a teacher, Rivera is today a teaching reference point for many young pianists, many of them already winners of piano competitions and international who train or perfect with him at the Accademia Musica Ritrovata in Livorno, the Accademia Stefano Strata in Pisa, the Accademia delle Arti Musicali in Sarzana (La Spezia) and in the numerous Master Classes he holds in Italy and abroad. In 2019, in Buenos Aires, he was awarded the prestigious Konex prize for artistic trajectory.