Rameshbabu Praggnanandhaa stunned the chess world this week after beating the No. 1 ranked player, Magnus Carlsen in an online championship.

CBS News reports that the 16-year-old is the youngest player to beat Carlson since he became world champion in 2013.

Carlson, who reportedly contracted COVID-19 ahead of the tournament, blamed the virus for his lackluster play.

"I don't have any energy and it was kind of hard to focus," Carlsen said, according to CBS News.

Praggnanandhaa has been considered an up-and-comer in the chess world for years.

At age 10, he became the younger international master in the game's history, CNN reported.