He won the 2006 Mantova Challenger tournament held on clay courts in Italy, where he defeated Giorgio Galimberti 6–2, 5-7, 6–4 in the final to win the championship.

Villagran made his ATP Tour debut at the 2005 Buenos Aires tournament on clay courts in Argentina where he was granted a wild card entry into doubles main draw alongside compatriot Juan Pablo Brzezicki.

They pulled off a major upset, defeating first seeds Gastón Etlis and Martín Rodríguez in the first round 2–6, 6-2, 6–3.

Two years later at the 2007 Buenos Aires Open he was given another wild card entry into the doubles draw, alongside Eduardo Schwank however they were defeated in the first round by Martin Garcia and Sebastián Prieto in three sets 4-6, 6–2, [12–14].

Villagrán was born and raised in Argentina, but went to compete in a tennis tournament in Neuchâtel, Switzerland.