[1][2][3] Alfonso won the gold medal at the 2019 European Games, defeating Stepan Hrekul, Mikhail Dauhaliavets, Ziad El Mohor, Simone Fiori and Benjamin Whittaker.

[6] At the European Olympic qualification in March 2020 in London, which was interrupted due to the COVID-19 pandemic and continued in June 2021 in Paris, Alfonso won the tournament with victories against Stepan Hrekul and Imam Khataev, as well as advancing without a fight due to the non-appearance of opponents Gazimagomed Jalidov and Benjamin Whittaker, thus qualifying him for the Summer Olympics in Tokyo.

[7][8] Competing in the men's light heavyweight event, he defeated Dilshodbek Ruzmetov and in the quarterfinals against Bayram Malkan, before being eliminated in the semifinals by Arlen López, winning a bronze medal.

He defeated Tawfiqullah Sulaimani of the Fair Chance Team, Andrei Arădoaie from Romania, Sharabutdin Ataev from Russia, Herich Ruiz from Cuba and Keno Machado from Brazil.

[10] He won another World Championship medal in 2023 in Tashkent, after losing to Ataev in the final fight and thus winning silver.