Joao Fonseca became the youngest ATP player to win a doubles title above 250 level since Roger Federer in 2001 (Rotterdam, with Bjorkman) when he paired with 42-year-old Marcelo Melo to defeat Constantin Franzen and Robin Haase in Sunday’s Rio doubles final.
The wild cards, who saved a match point in the semifinals to become the third all-Brazilian pair to compete in the title match at Rio, scored a 4-6, 6-3, 10-8 win that was sealed by a Fonseca ace that barely clipped both lines.
Fonseca, 19, becomes the youngest champion in Rio Open history, while Melo repeats as champion after claiming the title last year alongside Rafael Matos, and becomes the oldest doubles champion in tournament history.
| Player | Age | Title |
| João Fonseca | 19 | 2026 Rio Open w/Melo |
| Alexander Zverev | 21 | 2019 Acapulco w/M. Zverev |
| Sam Querrey | 22 | 2010 Memphis w/Isner |
| Rinky Hijikata | 22 | 2023 Tokyo w/Purcell |
| Jack Sock | 23 | 2015 Beijing w/Pospisil |
With the win, Melo becomes the second active player to have 40 ATP doubles titles.
| No. | Player | Titles |
| 1. | Mate Pavic | 42 |
| 2. | Marcelo Melo | 40 |
| 3. | Jean-Julien Rojer | 37 |
| 4. | Jamie Murray | 34 |
