President of the Austrian Football Association Leo Windtner sent his deep condolences, saying that Riedl was a brilliant player in his playing period, and he also did a great job as a coach abroad.
During his career, Riedl made many contributions to Austrian football as well as Vietnamese football.
As a player, Riedl was a striker who played four games for Austria. He coached Austria for eight games in 1990 and 1991, including a failed bid to qualify for the 1992 European Championship.
Riedl later worked as sporting director of the Iranian national team and as coach of Liechtenstein, Vietnam, Palestine, Laos and Indonesia, as well as with clubs from North Africa and Asia
Riedl led the Vietnamese football team in the periods of 1998-2000; 2003-2004 and 2005- 2007. He helped the team enter the quarterfinals of the AFC Asian Cup 2007.
The Austrian coach also helped Vietnam become runners-up at the 1998 Tiger Cup (now AFF Cup) after losing 0-1 to Singapore in the final in Hanoi, and win silver medals at the Southeast Asian Games (SEA Games) in 1999, 2003 and 2005.