1. Novak Djokovic

No one would've thought in their wildest dreams that Novak Djokovic might end 2018 as the World No.1. This guy was out of the top 20 in June!
But here we are, in October, and no one has a better chance at finishing as the year-end World No. 1 than this man. Djokovic's rise has been as dramatic as was his fall in 2016, where he shockingly went down after winning his first French Open title and becoming the first man after the great Rod Laver himself, to hold all the four Grand Slams together.
As soon as he announced his 'medical intervention' earlier this year, I had predicted that Djokovic will regain his form at Wimbledon. But I didn't expect him to win it altogether. Djokovic's form had returned in the French Open itself. In the match which he lost in the French Open, his game was pretty good. He only wasn't strong mentally due to which he lost.
But he regained that mentality and came all guns blazing at Wimbledon this year, where he defeated Nadal in the semi-finals, which is definitely in the top 3 Grand Slam matches this season. After that, he finally won the Cincinnati Masters, the only Masters level tournament that had eluded him (largely owing to Federer's success in the event). Then he went on to win the US Open as well, losing only 2 sets in the process.
He is now currently 1035 points behind Nadal in the Race To London rankings. Considering the fact that he is fit and has the form with him, I don't see anybody stopping Djokovic to end the year as the World No.1
Prediction: Ends the year as the World No.1
What is the foot injury that has troubled Rafael Nadal over the years? Check here