He faced Soviet boxer Stanislav Stepashkin, in the gold medal match and lost in a 3–2 controversial decision.

[1] His first fight as a professional was with Shigeo Nirasawa of Japan at the Araneta Coliseum in Cubao, Quezon City which took place on October 2, 1965, as part of Fiesta Fistiana, a fund raising event organized by the Philippine Sportswriters Association for disabled boxers.

[6] Anthony and his father filed a case against Ilang-Ilang Productions of Espiridion Laxa for P45,000 for "exploitation of popularity".

[6] Shortly after winning the silver medal, Villanueva went into an acting career, though at the cost of his amateur boxing license.

[8] He appeared in Malakas, Kaliwa't Kanan with Nida Blanca, Salonga Brothers with then actor Joseph Estrada.

He worked as a cook in a Mexican restaurant in Massachusetts, then as a security guard in Staten Island and the Philippine Consulate in New York City.

[11] Villanueva was bedridden due to multiple complications including kidney malfunction and severe heart ailments.

"[12] AIBA president Wu Ching-Kuo also said that the death of Villanueva not only left a void in Philippine boxing but also "in the hearts of all those who knew this hero around the world.