Answer
In 2003, Teimour Radjabov, who was then a 15-year-old chess prodigy, beat world number 1 Garry Kasparov in the Linares tournament. This was a major upset, as Kasparov was considered to be the greatest chess player of all time. Radjabov's victory was a sign of his immense talent, and he went on to become one of the world's top chess players.