What Rafael Nadal needs to do to stay on the heels of World No. 1 Roger Federer

Rafael Nadal had to hobble out of the Rod Laver Arena as he struggled with a hip problem during the Australian Open quarter-final match against Marin Cilic. Now, a month later, the Spanish star returns to action when he takes the court later tonight at Acapulco.

And while he was out injured, a lot happened in the world of tennis.

Roger Federer won the Australian Open as, with Nadal forced out and Novak Djokovic crashing out in the quarters, his route was cleared. By claiming his 20th Grand Slam title, the Swiss maestro was already breathing heavily down Nadal's neck at the top of the World rankings.

And, about a week back he toppled Nadal after beating Grigor Dimitrov in the final of the Rotterdam Open, a tournament he was initially not supposed to play. In the process, Federer became the oldest World No. 1 in the history of the sport.

There was no hint of trepidation when Nadal congratulated his foe on his incredible feat. In fact, he recently indicated that he is not looking to battle Federer and regain his world number one ranking. But somewhere he must have felt that tang of disappointment when he lost his crown and he must be vying to get back on the top.

Of course, with just 345 points separating the two, there is every possibility that Nadal might trump Federer, sooner rather than later, if he can win a few tournaments here and there beginning with the Mexican Open at Acapulco. But that, in itself, is an arduous task given the fact that Nadal, 31, is making a comeback from a recurring injury.

Although Federer is not taking part in the Mexican Open, Nadal still has to overcome a stellar line-up which includes Alexander Zverev, Dominic Thiem, Marin Cilic, Juan Martin del Potro and Kevin Anderson among others. And, with the Swiss maestro defending 2000 points over the coming weeks at Indian Wells and Miami, anything less than a title win will hurt Nadal's cause.

If Nadal does manage to win the Mexican Open, he will garner 500 points. However, he will not be able to surpass Federer as he will lose 300 points next Monday anyway. But a win at Acapulco will help Nadal apply some extra pressure and stay right on the heels of Federer, who has opted not to take part in this week's Dubai Open. Then, once the clay season starts, with Nadal's brilliance on the surface, anything can happen.

This begs the question, how long will Federer enjoy his stay at the top of the rankings? Even his father, Robert, was not convinced his son will be able to wear the crown for the entire season.

Looking at the Mexican Open draw, Nadal begins his campaign against compatriot Feliciano Lopez, a player who has won their last two meetings. In the second round, he could potentially face Thanasi Kokkinakis whereas defending champion Sam Querrey is a likely quarter-final opponent.

Sterner tests will await him in the semi-final, if he makes it there, in the form of Anderson, Jack Sock and 2018 Australian Open semifinalist Hyeon Chung. The other half of the draw also boasts of the likes of Zverev, Del Potro, Thiem and Nishikori, all of whom are perfectly capable of getting the better of the Spaniard.

It is no easy task, but the incentive of an opportunity to turn up the heat on Federer should be motivation enough for Nadal.