Adelaide: Unstoppable Serena Williams could eclipse Steffi Graf as the most successful Grand Slam champion in the Open era, tennis great Martina Navratilova said Tuesday.
Navratilova said she expects the American to equal her total of 18 Grand Slam singles titles at the Australian Open starting in Melbourne this month and go on to better Graf's record of 22. (Serena takes wrecking ball to rivals)
"If she can stay healthy there is no doubt she can go into the 20s. The sky is the limit," Navratilova told reporters in Adelaide.