Year-End Surge Shows Novak Djokovic Won't Give Up Men's Tennis Throne so Easily

2013 might have been the Year of Rafael Nadal, but since the U.S. Open, the ATP World Tour has belonged to Novak Djokovic.

Many casual fans might think that the tennis season ended when Nadal took out Djokovic in four sets in the U.S. Open final. However, there have been points, money and pride on the line in the last couple of months, and Djokovic has won them all.

The Serb is on an 18-match winning streak that spans five countries on two continents and includes two Davis Cup wins, two Masters Series titles and eight Top 10 victories. For some perspective, in the eight months prior to that he only had 11 Top 10 victories and one Masters Series title (out of seven tournaments).

That's not to say that the first three quarters of the year were bad for Djokovic—in fact, he had a year that most tennis players can only dream of. He held onto the No. 1 ranking until just last month. He won the Australian Open in January for his sixth major title. He made the semifinals of he French Open and the finals of Wimbledon and the U.S. Open. He is currently 68-9 on the year, with a chance to win 70 or more matches for the third year in a row.

But in the biggest moments at the last three slams of the year, Djokovic just couldn't come up with his best tennis. And, most notably, at the Masters Series, events that he had always excelled at in the past, Djokovic often looked ordinary. Losses to players such as Grigor Dimitrov, Tommy Haas and John Isner left many fans and journalists scratching their heads.

Still, most years he would have been able to get away with those sub-par performances because of his play at the Slams. But since Nadal came back onto the tour in February after a seven-month layoff and steamrolled through the competition, winning 10 titles, including five Masters 1000s and two Grand Slams, there was little-to-no margin for error.

In fact, after the U.S. Open, Nadal had a nearly 3,000-point lead in the ATP Race over Djokovic, a seemingly insurmountable gap. 

Mathematically, Djokovic knew the odds of ending the year as the No. 1 player were slim, but that didn't mean he had to walk quietly into the sunset of the season. 

Just a few days after he lost the heartbreaking U.S. Open final to Nadal, Djokovic was back home indoors in Serbia playing in the Davis Cup semifinals for his country. He scored two crucial victories without dropping a set to send his team into the final vs. the Czech Republic at the end of the year.

After just two weeks of rest, he was in Beijing, where he defeated Nadal in the final of the China Open to win his fourth title of the season. The next week at the Shanghai Masters, he defended his 2012 title by taking out Juan Martin del Potro in the final in a third-set tiebreaker.

Last week, Djokovic continued his streak of good fortune, surviving in-form opponents such as Isner, Roger Federer and David Ferrer to take his second title at the Paris Masters.

He might not have always played his best tennis at the end of the year—in fact, sometimes his play was down-right bizarre—but the Serb showed a patience and a focus that he often lacked this year. This calmness and determination has allowed him to get through the bad patches and come out the other side victorious.

On Tuesday, Djokovic got his World Tour Finals defense off to a winning start, surviving an inspired and suddenly in-form Federer to win his first Round Robin match. He's in a tough group with Federer, del Potro and Richard Gasquet, but he's still the favorite. Few would bet against Djokovic after his performances the last six weeks.

Nadal only has to win one more match at the World Tour Finals to secure his No. 1 spot for the year. But the Spaniard shouldn't get too comfortable in his perch at the top—as Djokovic has proved once again this fall, he's not going down without a fight.