#2 Zverev has had a relatively better junior career
There have been a number of top players on tour, who have come into the senior level on the back of a successful junior career, including the likes of Andy Murray and Roger Federer. Zverev, who has not enjoyed much success in his senior career, actually had a relatively good career on the junior circuit.
In juniors, the leftie reached a combined ranking of 3 and produced a few decent performances at Grand Slams. In singles, his best performance at a junior Grand Slam was reaching the semi-finals of the 2004 US Open, where he was beaten by Andy Murray. He also reached the quarter-finals of the French Open and Australian Open in 2004, where he was beaten by Alex Kuznetsov and Novak Djokovic respectively.
In doubles, Zverev reached the final of the 2004 French Open partnering Alex Kuznetsov, who had previously beaten him in the singles tournament. They lost to the Spanish duo of Marcel Granollers and Pablo Andujar in straight sets.