17 year old Russian Andrey Rublev just took out Fernando Verdasco in Barcelona, and it's looking like he's going to be a major factor in men's tennis over the next decade. Rublev displayed some of the best and most complete groundstrokes we've seen from a young player in quite some time, and seems well on his way to becoming a top tier ATP player. Not only does he crack the ball from both wings, but he takes the ball extremely early with great racket head speed. Players with his quality of groundstrokes don't come around very often, and the ATP Tour is better off when they do.
Brad Gilbert compared Rublev to the recently retired Nikolay Davydenko, and the comparison is a good one. Davydenko was known for his incredible ability to take the ball early off both sides, and had some of the best groundstrokes in the game despite his slight frame. Rublev has a respectable serve and appears to have decent movement (without being a freakish athlete a la Nadal or Djokovic), but possesses a forehand and backhand that many more established pros would take in a second.
Rublev will need to become more fit, as he started to cramp in his two-set victory over Verdasco. Nerves may have played a factor, but it's obvious that he won't hold up in grand slams unless he improves his conditioning. However, he's hardly the first 17 year old to have issues with fitness, and the vast majority of players figure it out by the time they hit their twenties. Rublev also displayed some strange celebrations (including the unique "full body fist-pump"), and will likely rub many players the wrong way if he continues these antics. However, tennis fans have long complained that the Big Four is too "gentlemanly", and can't have it both ways.
He may not end up being the best player out of the strong group of emereging teenagers, which includes Borna Coric, Alexander Zverev, Thanasi Kokkinakis, Nick Kyrgios, Jared Donaldson, Frances Tiafoe and a host of others, but none of them have Rublev's natural ability off the ground. If nothing else, they all better work on their fitness, because it looks like Rublev may have them on a string for the next ten years.