Challenger - Montevideo 11/09 17:50 25 [190] Renzo Olivo v Thiago Monteiro [95] 7-6,2-6,6-7
Challenger - Buenos Aires 10/24 16:00 29 [92] Thiago Monteiro v Sebastian Baez [124] 4-6,0-6
Challenger - Buenos Aires 10/23 16:55 28 [92] Thiago Monteiro v Francisco Cerundolo [116] 6-1,2-6,6-3
Challenger - Buenos Aires 10/22 15:00 27 [92] Thiago Monteiro v Tomas Martin Etcheverry [138] 6-4,3-6,7-5
Challenger - Buenos Aires 10/20 20:20 26 [92] Thiago Monteiro v Nicolas Kicker [259] 6-2,6-3
Challenger - Buenos Aires 10/19 15:40 25 [92] Thiago Monteiro v Hernan Casanova [331] 7-6,3-6,6-2
ATP - Indian Wells 10/07 19:55 23 [92] Thiago Monteiro v Tennys Sandgren [102] 4-6,3-6
Challenger - Lisabon 09/29 16:50 26 [90] Thiago Monteiro v Andrea Pellegrino [258] 3-6,6-7
Challenger - Lisabon 09/28 09:00 25 [90] Thiago Monteiro v Alexandre Muller [201] 6-4,6-4
Challenger - Braga 09/26 09:55 29 [90] Thiago Monteiro v Nikola Milojevic [148] 7-5,7-5
Challenger - Braga 09/25 11:35 28 [90] Thiago Monteiro v Hugo Gaston [115] 6-4,6-1
Challenger - Braga 09/24 11:55 27 [90] Thiago Monteiro v Andrea Arnaboldi [286] 4-6,6-4,6-2
Challenger - Braga 09/22 12:00 26 Thiago Monteiro v Tiago Cacao 6-1,6-1
Challenger - Braga 09/21 09:00 25 [90] Thiago Monteiro v Peter Heller [413] 6-3,6-3
Challenger - Štetín 09/16 14:00 26 [179] Marco Trungelliti v Thiago Monteiro [92] 6-4,6-3
Challenger - Štetín 09/13 13:50 25 [203] Steven Diez v Thiago Monteiro [92] 0-6,3-6
Challenger - Tulln 09/09 13:30 27 [242] Mats Moraing v Thiago Monteiro [93] 6-1,0-6,7-6
Challenger - Tulln 09/08 10:45 26 [236] Lukáš Rosol v Thiago Monteiro [93] 6-7,1-6
Challenger - Tulln 09/07 14:35 25 [282] Matthias Bachinger v Thiago Monteiro [93] 6-3,1-6,1-6
US Open 08/30 15:00 23 [93] Thiago Monteiro v Daniel Evans [27] 3-6,7-6,4-6,1-6
ATP - Winston-Salem 08/25 23:00 26 [51] Frances Tiafoe v Thiago Monteiro [93] 7-5,7-6
ATP - Winston-Salem 08/25 02:10 25 Thiago Monteiro v Eduardo Nava 7-5,6-1
ATP - Winston-Salem 08/22 21:20 24 [94] Thiago Monteiro v James Duckworth [69] 6-4,4-6,7-6
ATP - Cincinnati 08/14 15:35 14 [54] Carlos Alcaraz v Thiago Monteiro [94] 6-2,6-3
Olympijské hry 2020 - muži 07/24 04:25 24 [48] Jan-Lennard Struff v Thiago Monteiro [95] 6-3,6-4
ATP - Bastad 07/12 11:00 25 [107] Yannick Hanfmann v Thiago Monteiro [93] 6-2,7-5
Challenger - Salzburg 07/06 11:20 25 [81] Thiago Monteiro v Nicolas Jarry [309] 7-6,6-7,6-7
Wimbledon 06/30 13:55 23 [19] Felix Auger Aliassime v Thiago Monteiro [81] 6-3,6-3,6-3
French Open 06/02 16:50 24 [80] Thiago Monteiro v Steve Johnson [88] 3-6,7-6,6-7,6-3,3-6
French Open 05/31 09:00 23 [117] Francisco Cerundolo v Thiago Monteiro [80] 3-6,4-6,3-6

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.