World number one tennis player Novak Djokovic has expressed contempt for the actions of cyclist Lance Armstrong.

The American came clean about the use of performance-enhancing drugs during an interview with Oprah Winfrey

Armstrong admitted to using banned substances during his seven wins at the Tour de France between 1999 and 2005, backtracking on years of doping denials.

Djokovic, speaking after his 6-4 6-4 7-5 victory over Radek Stepanek at the Australian Open, believes that the American "cheated" the sport and its fans.

"He cheated the sport, many people around the world," said Djokovic. "I think he should suffer for his lies all these years."

Part two of Armstrong's interview with Oprah airs tomorrow.