At the tournament in Chennai in 2006 he reached the semifinals. In May 2006, he moved into the final in Munich , where he lost the first Belgian men's individual final in the history of the ATP Tour against Olivier Rochus . Viegen reached a total of four finals in his career, two each in the singles and doubles competition. However, he was denied a tournament victory on the ATP Tour. Due to persistent injury problems, Viegen ended his career on July 14, 2011.
Davis Cup 2007
In the 1st round of the Davis Cup 2007 Kristof Viegen was the guarantee for the 3-2 victory over Australia . He defeated Lleyton Hewitt 4: 6, 6: 4, 3: 6, 6: 3, 6: 4 and finally won against Chris Guccione , whom he defeated 6: 4, 6: 4, 6: 4 Point. In the quarterfinals he lost on April 6 in the game against Germany against Tommy Haas .