Top 5 contenders for No. 1 ranking in Men's Tennis in 2018

#3 Alexander Zverev

Alexander Zverev has taken the ATP circuit by storm at a very young age

The German wonderkid has been making all the right noises of late. He announced himself at the world stage last year by becoming the youngest player since Djokovic to capture multiple Masters 1000 crowns in a single season. He defeated Djokovic and Federer to win titles at Rome and Montreal respectively and compiled an impressive 55-22 year-end record.

The 20-year-old world no. 5 has made it to the Miami finals this year, and a win against Isner will propel him to world no. 3. With a whole lot of season still to play, this might as well be Zverev's year at the top.

Although there is a steep challenge in the form of Nadal on clay and Federer on grass, Zverev has been high on form and confidence and with improved consistency can provide the big boys a run for their money.

Typically a good hard-court player, Zverev has proved his mettle on clay too and would look to capture valuable points in the next couple of months. Among the younger lot, Zverev has by far made the biggest impact on tour, coming ahead of the likes of Dominic Thiem and Borna Coric.

A better run at Grand Slams this year would further consolidate his position at the top, and with a bit of luck going his way, we might witness him being the first World No. 1 outside the Big Four.