The 18-time Grand Slam singles champion said she didn't watch Armstrong's US TV interview with Oprah Winfrey, during which he admitted to doping during his seven Tour de France wins, because she'd already made up her mind about him.

“There is no justification for what he did,” Navratilova said. “Lying about it with such conviction for so many years, suing people and winning and just denying it so many times, I mean, it takes some serious ego to be able to do that. Clearly, he has a big ego.

“He should never be able to compete anywhere at any level. If it was just a one-time deal, OK, but every year he raced, he was cheating. It's unimaginable.”

Navratilova is in Melbourne to play in the Australian Open legends doubles event. She's confident tennis is a clean sport, but thinks anti-doping authorities should be giving players blood tests on a more consistent basis.

When told that men's No. 1 Novak Djokovic said he hadn't received a blood test in six months, Navratilova said: “He shouldn't be slipping through the cracks that much.

“Some people may be tested once a month and then some get tested maybe once or twice a year,” she said. Anti-doping authorities “need to figure that out a little bit better, but overall I think tennis is in pretty good hands”.

Navratilova is teaming with that other famous Martina, five-time major winner Martina Hingis, in the legends doubles event.