#2 Alexander Zverev
Alexander Zverev had his best year in 2017, winning 5 titles and reaching a career-high ranking of World No. 3 before finishing the year at No. 4. He has been singled out by many players and commentators, as one of the apparent heirs to the Big 4 and a future World No. 1.
The 20-year-old won his first two Masters 1000 titles last year at the Italian Open, by defeating Djokovic, and at the Canadian Open, by defeating Federer. He is the youngest player since Djokovic in 2007 to win an ATP 1000 title and the first player born in the 1990s to do so.
The German's best Grand Slam showing was the 4th Round at last year's Wimbledon. He will be looking to improve on that in 2018. Zverev is primarily a baseline player. However, he is good at the net as well. He is a strong server and is known for his tenacity on the court.
He will be out to prove that 2017 was not a fluke.