Jaime Oncins (born 16 June 1970) 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 (Bologna and Búzios, both in 1992). 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
Career finals
Singles (2)
| Legend |
| Grand Slam (0–0) |
| Tennis Masters Cup (0–0) |
| ATP Masters Series (0–0) |
| ATP International Series Gold (0–0) |
| ATP Tour (2–3) |
|
| Titles by Surface |
| Hard (1–3) |
| Grass (0–0) |
| Clay (1–0) |
| Carpet (0–0) |
|
| Result |
No. |
Date |
Tournament |
Surface |
Opponent |
Score |
|---|
| Loss |
1. |
October 28, 1991 |
Búzios, Brazil |
Hard |
 Jordi Arrese |
6–1, 4–6, 0–6 |
| Loss |
2. |
November 4, 1991 |
São Paulo, Brazil |
Hard |
 Christian Miniussi |
6–2, 3–6, 4–6 |
| Win |
1. |
May 18, 1992 |
Bologna, Italy |
Clay |
 Renzo Furlan |
6–2, 6–4 |
| Win |
2. |
November 2, 1992 |
Búzios, Brazil |
Hard |
 Luis Herrera |
6–3, 6–2 |
| Loss |
3. |
November 9, 1992 |
São Paulo, Brazil |
Hard |
 Luiz Mattar |
1–6, 4–6 |
Doubles (5)
| Legend |
| Grand Slam (0–0) |
| Tennis Masters Cup (0–0) |
| ATP Masters Series (0–0) |
| ATP International Series Gold (1–0) |
| ATP Tour (5–6) |
|
| Titles by Surface |
| Hard (1–1) |
| Grass (0–0) |
| Clay (4–5) |
| Carpet (0–0) |
|
| Result |
No. |
Date |
Tournament |
Surface |
Partner |
Opponents |
Score |
|---|
| Loss |
1. |
December 31, 1990 |
Wellington, New Zealand |
Hard |
 John Letts |
Luiz Mattar
 Nicolás Pereira |
6–4, 6–7, 2–6 |
| Loss |
2. |
April 29, 1991 |
Madrid, Spain |
Clay |
Luiz Mattar |
Gustavo Luza
Cássio Motta |
0–6, 5–7 |
| Loss |
3. |
May 20, 1991 |
Bologna, Italy |
Clay |
Luiz Mattar |
Luke Jensen
Laurie Warder |
4–6, 6–7 |
| Win |
1. |
November 4, 1991 |
São Paulo, Brazil |
Hard |
 Andrés Gómez |
Jorge Lozano
Cássio Motta |
7–5, 6–4 |
| Win |
2. |
February 22, 1993 |
Mexico City, Mexico |
Clay |
Leonardo Lavalle |
Horacio de la Peña
Jorge Lozano |
7–6, 6–4 |
| Loss |
4. |
August 2, 1993 |
Prague, Czech Republic |
Clay |
Jorge Lozano |
 Hendrik Jan Davids
 Libor Pimek |
3–6, 6–7 |
| Win |
3. |
March 22, 1999 |
Casablanca, Morocco |
Clay |
Fernando Meligeni |
Massimo Ardinghi
Vincenzo Santopadre |
6–2, 6–3 |
| Win |
4. |
June 7, 1999 |
Merano, Italy |
Clay |
Lucas Arnold Ker |
 Marc-Kevin Goellner
Eric Taíno |
6–4, 7–6 |
| Win |
5. |
July 19, 1999 |
Stuttgart, Germany |
Clay |
Daniel Orsanic |
 Aleksandar Kitinov
Jack Waite |
6–2, 6–1 |
| Loss |
5. |
April 30, 2001 |
Munich, Germany |
Clay |
Daniel Orsanic |
Petr Luxa
Radek Štěpánek |
7–5, 2–6, 6–7(5–7) |
| Loss |
6. |
May 20, 2001 |
Sankt Pölten, Austria |
Clay |
Daniel Orsanic |
Petr Pála
David Rikl |
3–6, 7–5, 5–7 |
