French Open 10/01 09:00 24 [96] Marcos Giron v Thiago Monteiro [84] 6-7,4-6,1-6
French Open 09/29 15:20 23 [84] Thiago Monteiro v Nikoloz Basilashvili [33] 7-5,6-4,6-2
Challenger Forli 09/26 10:00 29 [180] Lorenzo Musetti v Thiago Monteiro [89] 7-6,7-6
Challenger Forli 09/25 08:00 28 [89] Thiago Monteiro v Andrea Pellegrino [343] 6-4,4-6,6-1
Challenger Forli 09/24 10:55 27 [89] Thiago Monteiro v Alexander Ritschard [319] 7-6,6-3
Challenger Forli 09/23 09:35 26 [89] Thiago Monteiro v Riccardo Bonadio [278] 2-6,7-6,6-4
Challenger Forli 09/21 10:30 25 [94] Yuichi Sugita v Thiago Monteiro [88] 1-6,6-7
Challenger Forli 09/20 10:20 164 [88] Thiago Monteiro v Raul Brancaccio [387] 6-2,7-6
Challenger Forli 09/19 13:40 64 [88] Thiago Monteiro v Francesco Forti [433] 6-3,6-3
ATP Rome 09/12 15:25 14 [112] Taro Daniel v Thiago Monteiro [83] 4-6,7-6,6-4
ATP Kitzbuhel 09/08 10:10 19 [83] Thiago Monteiro v Yannick Hanfmann [118] 1-6,6-2,3-6
ATP Kitzbuhel 09/07 14:55 14 [83] Thiago Monteiro v Lucas Miedler [295] 6-2,6-7,7-5
US Open 09/01 17:50 23 [21] Felix Auger Aliassime v Thiago Monteiro [83] 6-3,6-7,7-6,7-6
ATP New York 08/21 17:30 19 [101] Emil Ruusuvuori v Thiago Monteiro [82] Retired
ATP New York 08/20 21:30 - [104] Federico Coria v Thiago Monteiro [82] 3-6,4-6
Davis Cup 03/07 05:00 45 [43] John Millman v Thiago Monteiro [82] 6-7,7-6,7-6
Davis Cup 03/06 02:30 45 [63] Jordan Thompson v Thiago Monteiro [82] 6-4,6-4
ATP Santiago 02/28 17:20 27 [88] Thiago Monteiro v Albert Ramos-Vinolas [45] 4-6,4-6
ATP Santiago 02/27 16:00 26 [88] Thiago Monteiro v Roberto Carballes Baena [97] 6-1,6-4
ATP Santiago 02/25 16:00 25 [88] Thiago Monteiro v Leonardo Mayer [111] 6-7,6-3,6-4
ATP Rio De Janeiro 02/19 22:00 26 [88] Thiago Monteiro v Attila Balazs [106] 6-1,1-6,4-6
ATP Rio De Janeiro 02/19 00:20 25 [26] Guido Pella v Thiago Monteiro [88] 7-5,4-6,6-7
ATP Buenos Aires 02/15 02:05 27 [92] Thiago Monteiro v Pedro Sousa [145] 6-7,4-6
ATP Buenos Aires 02/13 00:00 26 [31] Borna Coric v Thiago Monteiro [92] 4-6,6-7
ATP Buenos Aires 02/10 17:30 25 [95] Jaume Munar v Thiago Monteiro [92] 3-6,3-6
ATP Cordoba 02/04 19:30 25 [71] Corentin Moutet v Thiago Monteiro [89] 6-4,6-3
Challenger Punta del Este 02/02 21:30 29 [77] Marco Cecchinato v Thiago Monteiro [86] 6-7,7-6,5-7
Challenger Punta del Este 02/02 00:35 28 [388] Felipe M R Alves v Thiago Monteiro [86] 3-6,3-6
Challenger Punta del Este 02/01 00:00 27 [328] Guilherme Clezar v Thiago Monteiro [86] 4-6,1-6
Challenger Punta del Este 01/30 22:45 26 [228] Francisco Cerundolo v Thiago Monteiro [86] 5-7,4-6

Thiago Moura Monteiro (Brazilian Portuguese: [tʃiˈaɡu mõˈtejɾu]; born 31 May 1994) is a Brazilian professional tennis player.

Monteiro has a career-high ATP singles ranking of world No. 61 achieved on 17 October 2022. He also has a career-high ATP doubles ranking of No. 144, achieved on 31 January 2022. He is currently the No. 2 Brazilian tennis player.

On the ITF Junior Circuit, Monteiro peaked in the rankings at No. 2 on 2 February 2012, with his biggest junior singles title being the Grade A, Copa Gerdau in Porto Alegre, Brazil, in 2011.

In his first ATP match, as a wildcard ranked world No. 338 in the ATP 500 Rio de Janeiro in February 2016, Monteiro upset No. 9 Jo-Wilfried Tsonga in the first round. In the second round, Monteiro lost to eventual champion Pablo Cuevas. In his next tournament, the ATP 250 São Paulo, Monteiro won two matches (against former World No. 9 Nicolás Almagro, and Daniel Muñoz de la Nava), losing again to eventual champion Cuevas in the quarterfinals.

On May 8, 2016, Monteiro won his first ATP Challenger title in Aix-en-Provence, France. He defeated Carlos Berlocq in the final.