Jaime Oncins
Jaime Oncins is a former professional tennis player from Brazil.
Oncins represented his native country at the 1992 Summer Olympics in Barcelona, where he reached the quarterfinals before falling to Russia's Andrei Cherkasov. The right-hander won two individual career titles. He reached his highest singles ATP-ranking on May 3, 1993, when he became world no. 34.
Oncins' best performance at a major was at the 1992 French Open, where he reached the Round of 16, losing to eventual finalist, Petr Korda. In the second round of the tournament, Oncins had a famous victory from two sets down against former world no. 1 and three-time French Open champion, Ivan Lendl. Oncins was also the last player that Jimmy Connors beat at the US Open. Connors beat Oncins in straight sets in the first round of the 1992 US Open, which was on Connors' 40th birthday.
Oncins was a runner-up in the Roland Garros mixed doubles event in 2001, with Paola Suárez from Argentina.
Grand Slam mixed doubles finals
Runners-up (1)
Career finals
Singles (2 wins, 3 losses)
| Result | No. | Date | Tournament | Surface | Opponent | Score |
| Loss | 1. | Oct 1991 | Búzios, Brazil | Hard |  Jordi Arrese | 6–1, 4–6, 0–6 |
| Loss | 2. | Nov 1991 | São Paulo, Brazil | Hard |  Christian Miniussi | 6–2, 3–6, 4–6 |
| Win | 1. | May 1992 | Bologna, Italy | Clay |  Renzo Furlan | 6–2, 6–4 |
| Win | 2. | Nov 1992 | Búzios, Brazil | Hard |  Luis Herrera | 6–3, 6–2 |
| Loss | 3. | Nov 1992 | São Paulo, Brazil | Hard |  Luiz Mattar | 1–6, 4–6 |
Doubles (5 wins, 6 losses)
| Result | No. | Date | Tournament | Surface | Partner | Opponents | Score |
| Loss | 1. | Dec 1990 | Wellington, New Zealand | Hard |  John Letts | Luiz Mattar  Nicolás Pereira | 6–4, 6–7, 2–6 |
| Loss | 2. | Apr 1991 | Madrid, Spain | Clay | Luiz Mattar | Gustavo Luza Cássio Motta | 0–6, 5–7 |
| Loss | 3. | May 1991 | Bologna, Italy | Clay | Luiz Mattar | Luke Jensen Laurie Warder | 4–6, 6–7 |
| Win | 1. | Nov 1991 | São Paulo, Brazil | Hard |  Andrés Gómez | Jorge Lozano Cássio Motta | 7–5, 6–4 |
| Win | 2. | Feb 1993 | Mexico City, Mexico | Clay | Leonardo Lavalle | Horacio de la Peña Jorge Lozano | 7–6, 6–4 |
| Loss | 4. | Aug 1993 | Prague, Czech Republic | Clay | Jorge Lozano |  Hendrik Jan Davids  Libor Pimek | 3–6, 6–7 |
| Win | 3. | Mar 1999 | Casablanca, Morocco | Clay | Fernando Meligeni | Massimo Ardinghi Vincenzo Santopadre | 6–2, 6–3 |
| Win | 4. | Jun 1999 | Merano, Italy | Clay | Lucas Arnold Ker |  Marc-Kevin Goellner Eric Taino | 6–4, 7–6 |
| Win | 5. | Jul 1999 | Stuttgart, Germany | Clay | Daniel Orsanic |  Aleksandar Kitinov Jack Waite | 6–2, 6–1 |
| Loss | 5. | Apr 2001 | Munich, Germany | Clay | Daniel Orsanic |  Petr Luxa Radek Štěpánek | 7–5, 2–6, 6–7 |
| Loss | 6. | May 2001 | Sankt Pölten, Austria | Clay | Daniel Orsanic | Petr Pála David Rikl | 3–6, 7–5, 5–7 |