Djokovic did just that, beating Nadal in a grueling final for the second time in three weeks to stay undefeated this year.
The victory Sunday at the Sony Ericsson Open marked the end of the American hard court season to start the year. Now the sport moves to clay, where Nadal remains the man to beat.
Djokovic is 24-0 in 2011, the best record to start a year since Ivan Lendl swept his first 25 matches in 1986. Djokovic has won 59 of 65 sets and four tournament titles on three continents.
Stamina and breathing difficulties were issues in the past for the slender Serb. By outlasting Nadal in a match that lasted nearly 3½ hours in 85-degree sunshine, Djokovic showed he's fit enough for the grinding clay marathons to come.
"He can run to every ball," Nadal said. "Seems like he's less tired than before when he runs a lot. He can play long points and still be running."
Even so, Nadal remains the player to beat on tennis' most physically demanding surface. During the spring clay season last year, the Spaniard went 22-0 and won four tournaments, including the French Open.
He became the first man to win titles at Monte Carlo, Rome and Madrid in the same season. Then he became the first man to win five Roland Garros titles in six years.
Nadal's reign on clay is the reason he's still ranked No. 1, even though he hasn't won a tournament since Tokyo in October. hoarse
Djokovic is No. 2, but no one disputes he has been the game's best player in 2011 — so far.
"It's pretty incredible, to be honest," said American Mardy Fish, who lost to Djokovic in the Key Biscayne semifinals. "He's hitting his forehand as good as anyone in the world. His two-handed backhand is the best in the world, in my opinion. And he's serving well again. He had some serving trouble last year at this time. He has certainly rectified that.
"When you watch him play, it's really not that surprising he hasn't lost yet, because he's playing so well."
Djokovic is 8-0 against top-10 opponents this year, including three wins over Roger Federer and two against Nadal. Djokovic won his second Grand Slam title at the Australian Open in January. He beat Nadal in the final at Indian Wells, and he's the first man to win that tournament and Key Biscayne back to back since Federer in 2006.
Those achievements came on hard courts, Djokovic's best surface. On clay he's 0-9 against Nadal.
"Rafa moves better on a clay court," Fish said. "It will be interesting to see Novak's results there. But you'd certainly be hard-pressed to find somebody that's moving better and more confidently than him right now on hard courts."
It's not Federer, who slipped to third in the rankings last month and then played poorly in a semifinal loss to Nadal at Key Biscayne. This year Federer is 0-3 against Djokovic and 0-2 against Nadal, and he hasn't won a clay title since his historic victory at the French Open in 2009.
Djokovic has won four of his 22 career titles on clay, the most recent coming in his native Belgrade two years ago. But he yet to reach a final at the French Open, losing in the quarterfinals last year and in the third round in 2009.
"Clay courts are where I haven't had a lot of success," he conceded.
With penetrating groundstrokes, one of the best drop shots in tennis and tremendous defensive skills, Djokovic has the tools to win on the surface that demands the most patience and shotmaking variety.
Lack of fitness was often Djokovic's downfall in the past. Last year he retired during a quarterfinal match at Belgrade because of breathing problems, then skipped Madrid's clay event. hoarse
But it was Nadal, not Djokovic, hunched over with fatigue late in their match Sunday. And it's Djokovic who takes a winning streak into the clay season.
"Rafa is definitely the best player in the world," Djokovic said. "If I want to have the No. 1 ranking, I need to play consistently well throughout the whole year. We all know that clay is his favorite surface, and obviously where he plays his best. But this is going to give a lot of confidence boost for the clay season."
For Djokovic, it starts next week at Monte Carlo, a tournament Nadal has won the past six years. Nadal is 19-4 in 2011 and said the early season swing in the United States was the best of his career, even though he's 0-2 in finals this year.
That could soon change.
"I'm seriously happy about how I'm playing," Nadal said. "Normally when I play well on clay I have a little bit more advantage, so let's see."