Career
Orešar had a highly successful junior tennis career. At one time he was the number one ranked junior in the world. Orešar"s senior career was less successful.
Apart from winning two gold medals in the 1987 Summer Universiade (in singles and in mixed doubles with Sabrina Goleš), his biggest singles tournament successes were reaching the finals of Athens and Båstad in 1988 and 1989 respectively.
A persistent back injury forced him into early retirement from professional tennis in 1991. His highest Association of Tennis Professionals ranking was #46 in May 1989.
In the early 1990s Orešar took part in founding the Croatian Tennis Association and coached the Croatian national tennis team In 1995 he bought Jadrankamen, a Brač-based quarrying company, and expanded further into construction and tourism.
In 2005 he made the list of 1000 most powerful people in Croatia, compiled by Nacional weekly.
Singles (2 runners-up).