Well, to discuss tennis itself the USA youth players are up & coming but we don't have many elite type players like an Agassi or Sampras or Roddick. We do have a few of what appears to be solid upcoming players 19 years of age & under.
Right now, Jack Sock at 23 years of age & 26th place ranking is the top younger player:
http://www.atpworldtour.com/en/playe.../sm25/overview
John Isner is actually ranked higher than Sock but he's older so I didn't include him. This post will be for our younger players with promise.
Taylor Fritz is our top upcoming player at 18 years of age & currently ranked 64th in the world:
http://www.atpworldtour.com/en/playe.../fb98/overview
Dennis Novikov is a 22 year old who is ranked 128th in the world:
http://www.atpworldtour.com/en/playe.../n674/overview
Jared Donaldson is a 19 year old player who is currently ranked 145th in the world:
http://www.atpworldtour.com/en/playe.../dc58/overview
Frances Tiafoe is an 18 year old player who is ranked 157th in the world:
http://www.atpworldtour.com/en/playe.../td51/overview
Stefan Kozlov is also an 18 year old player who is ranked 169th in the world:
http://www.atpworldtour.com/en/playe.../ke64/overview
Noah Rubin is a 20 year old player who is ranked 181st in the world:
http://www.atpworldtour.com/en/playe.../rc96/overview
Tommy Paul is a 19 year old player who's ranked 203rd in the world:
http://www.atpworldtour.com/en/playe.../pl56/overview
Ernesto Escobedo is a player that's 20 years of age & ranked 266th in the world:
http://www.atpworldtour.com/en/playe.../e873/overview
Those are the top up & coming American tennis players we have coming. I don't think we have but maybe one of these that could become an elite player like an Agassi or Sampras. That player is Taylor Fritz.
He's only 18 right now & ranked 64th & also moving forward in the rankings & not downward. He has the best all around game of them all to become a top 10 tennis player in the world. He's already won several junior tournaments. He's also reached an ATP final on pro tour as the 2nd youngest American ever to accomplish this feat.
Fritz idolized Roger Federer growing up so he tries to imitate Federer's game on the court. He's a big guy at 6'4" & his serve can reach 130+ MPH. I would predict with his playing style by the time he's 20 years of age Fritz will be a top 15 player in the world & by 22 years of age he will be top 10. Will he ever be #1 ranked? I don't know but his game has that possibility.
One other young American to keep an eye on is Tommy Paul. He's only 19 years of age so he's young as well. Both Paul & Fritz have had some battles on the court during juniors. They each have beaten the other a few times. Paul beat Fritz to win the 2015 French Open juniors while Fritz turned that around at the 2015 US Open by defeating Paul.
Paul is a littler shorter than Fritz at 6'2" but he like Fritz has an all around tennis game. His bread & butter is his two-handed backhand just like Fritz. He's not as big of a server as Fritz either but still can hit 120+ MPH on the radar gun.
These two guys(Fritz & Paul) are what I consider to be the top tier of American tennis coming up. I wouldn't at all be surprised to see them both ranked in the top 20 within the next 2-3 years with what I believe as Fritz having the best chance to reach the top 10 & possible #1 overall ranking. Thanks!