This title allowed him to compete for the South American Championships in 1995 where he won gold in the singles bringing him to the attention of the Brazilian National Team, which he joined in 1998.

[5] Thiago participated in the 2004 Summer Olympics in Athens, Greece but was eliminated by Li Ching (Hong Kong) losing 4 - 1 in the second round.

[6][7] Monteiro achieved a great result at the 2015 World Table Tennis Championships, where, playing alongside Cazuo Matsumoto, he reached the quarterfinals of the doubles tournament, only being eliminated by the Korean duo, who finished with bronze.

With this, they repeated the feat of Dagoberto Midosi and Ivan Severo, who, in 1954, also reached this stage in the World Championship held in Wembley, England.

[10][11] At the 2004 Table Tennis World Cup, held in Hangzhou, China, he beat Olympic champion Seung Min Ryu, from South Korea, by 4 sets to 3 (5-11, 10-12, 11-8, 11-6, 8-11, 11-8, 11-8).