Maria Sharapova, Freddy Adu, LeBron James Among Most Successful Young Professional Athletes (Gallery)

Even with all of the years that professional athletes spend practicing, growing and learning their game, every now and then a rare young athlete seems to bypass the process. These upstarts can compete with much older and more experienced players.

We label these athletes "phenoms" and "sensations" and watch their every move as they enter professional leagues.

Most recently, 14-year-old Andy Zhang made history by qualifying for the U.S. Open. Zhang became the youngest participant in the major championship's history, and although he hasn't even swung a club yet, people are already anxiously awaiting his arrival in the golf world.

Plenty of athletes before Zhang have been able to make the jump from teenage years to professional sports. Some have been failed experiments, but others blossomed into superstars. From tennis sensations such as Maria Sharapova to athletes who were supposed to change the landscape of their sport such as Freddy Adu, these young guns are what make professional sports exciting. They show us that a star athlete can truly come from anywhere, at any time.

Click here to see the most successful young athletes of all time >>