His first trophy with the Italian team was at the 1989 Men's European Volleyball Championship in Sweden, where they topped their preliminary group with only one loss and went through the knockout stage up to the final where they beat 3–1 the host side[3] to win their first ever official tournament.

After the 1996 Summer Olympics, where the Italians won silver, he switched to the Italy women's team, from 1996 to 1997, coaching them to a gold medal at the Mediterranean Games.

[6] In 2024, he was formally appointed head coach of the Italy women's national volleyball team, with the goal of guiding them to the 2024 Summer Olympics.

After the 1976 Argentine coup d'état he had to live in semi-clandestinity because of his previous political involvement, a situation that compelled him to move to Buenos Aires where he got his first volleyball coaching job.

When he lived in Italy, Guardiola once travelled hundreds of kilometres so that he could meet Argentine volleyball coach Julio Velasco personally, simply because he had seen him in a TV interview and wanted to learn from him.