Joao Fonseca defeated Thiago Monteiro 7–6, 6–1 in the first round of the ATP 250 Rio de Janeiro tournament on clay on 17 February 2026. As the pre-match favourite with odds of 1.3, Fonseca delivered an expected victory, though Monteiro offered modest resistance in a competitive opening set that went to a tiebreak before the Brazilian asserted control in the second. The dominant second-set performance underscored Fonseca's superiority on home soil, where conditions favour his game. The result advances Fonseca deeper into his home tournament, reinforcing his status as a leading contender at this level.