The changing of the guard, which has been anticipated ever since Novak Djokovic embarked on his extraordinary unbeaten run, could take place as early as next weekend. If he wins his seventh tournament in succession here at the Rome Masters and Rafael Nadal fails to make the semi-finals, the 23-year-old Serb will replace the 24-year-old Spaniard as world No 1 next Monday.
Until Nadal lost to Djokovic in Sunday's final of the Madrid Masters the current world No 1 was still the undisputed king of clay, having not lost on his favourite surface for nearly two years. Now, however, he will go into the French Open in 12 days' time as less of a clear-cut favourite.
Having won on hard courts in Melbourne, Dubai, Indian Wells and Miami, Djokovic has put himself within touching distance of the No 1 ranking by winning his first two clay-court tournaments of the year.
"If I keep winning I'll get closer, but I'm trying not to think about that," Djokovic said, having extended his unbeaten run to 34 matches. "It was a perfect start with the two tournaments that I won and I need to stay dedicated and focused."
Nadal, who had beaten Djokovic in all nine of their previous meetings on clay, said the battle to keep his No 1 ranking was "finished". Djokovic could even take over at the top if his rival successfully defends his titles here and at Roland Garros.
Andy Roddick is among those astonished by what Djokovic is doing. "It's unbelievable. In his head he's in a perfect place right now," he said.