Giannini played with Fabiola Ramos at the 2002 Central American and Caribbean Games, winning the gold medal in mixed doubles.[1] He also played the team competition with Henry Mujica, Ricardo Lizardo, Jonathan Pino, winning the championship of the event.[2] He also took part of the 2004 Latin American Championship, claiming the bronze medal in the mixed doubles with Fabiola Ramos, and ranking among the 9-16th position in singles and 7th in team competition with Henry Mujica and Jonathan Pino.[3]
In the 2005 World Championships, he played the mixed doubles with Fabiola Ramos, defeating Italian Andrea Tarocco and Lao's Soulinda Sisavath 3-0 in the round of 64,[4] 3-2 to Rachid El Boubou and Lara Kejebachian from Libia,[5] 3-1 to Philippines's Ernesto Ebuen and Sendrina Balatbat,[6] but fell to Hong Kong's Li Ching and Lau Sui-fei 0-4 in the main draw round of 128.[7]
In November 2012 he won the silver medal with Ricardo Lizardo, Jepherson Roach y Miguel Arcones in the team competition of the Latin American Master Championship.[8]
