Marcos Ondruska
Marcos Ondruska is a former tennis player from South Africa, who turned professional in 1989. He represented his native country at the 1996 Summer Olympics in Atlanta, Georgia, where he defeated Goran Ivanišević in the first round before falling to Norway's Christian Ruud. The right-hander won four career titles in doubles, and reached his highest singles ATP-ranking on 10 May 1993, when he became the number 27 of the world.
Ondruska has a 13–7 career Davis Cup record in 11 ties.
Career finals
Singles (3 runner-ups)
| Result | No. | Date | Tournament | Surface | Opponent | Score |
| Loss | 1. | September 1992 | Cologne, Germany | Clay |  Bernd Karbacher | 6–7, 4–6 |
| Loss | 2. | March 1993 | Scottsdale, United States | Hard |  Andre Agassi | 2–6, 6–3, 6–3 |
| Loss | 3. | October 1996 | Tel Aviv, Israel | Hard |  Javier Sánchez | 4–6, 5–7 |
Doubles (4 titles, 2 runner-ups)
| Result | No. | Year | Tournament | Surface | Partner | Opponents | Score |
| Loss | 1. | February 1993 | Philadelphia, United States | Carpet | Brad Pearce | Jim Grabb Richey Reneberg | 7–6, 3–6, 0–6 |
| Loss | 2. | March 1993 | Durban, South Africa | Hard |  Johan de Beer | Lan Bale Wayne Black | 6–7, 2–6 |
| Winner | 3. | January 1996 | Auckland, New Zealand | Hard | Jack Waite |  Jonas Björkman Brett Steven | walkover |
| Winner | 4. | September 1996 | Palermo, Italy | Clay |  Andrew Kratzmann |  Cristian Brandi Emilio Sánchez | 7–6, 6–4 |
| Winner | 5. | October 1996 | Tel Aviv, Israel | Hard |  Grant Stafford |  Noam Behr Eyal Erlich | 6–3, 6–2 |
| Winner | 6. | August 1997 | Long Island, United States | Hard | David Prinosil | Mark Keil T. J. Middleton | 6–4, 6–4 |