Teen prodigy Jakub Mensik has caused a massive upset, defeating world No.6 Casper Ruud in the second round of the Australian Open.

Playing on Margaret Court Arena, Mensik was clinical with a 6-2, 3-6, 6-1, 6-4 victory.

The 19-year-old’s triumph came on the same court that Joao Fonseca defeated Andrey Rublev the night before as two top-10 males stars were sent packing.

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As Mensik pushed his way to a 6-1 win in the third set, former Australian tennis player John Fitzgerald delivered high praise to the Czech youngster.

“At times we all get ahead of ourselves but this kid to me looks like he could be a future grand slam champion. He’s a serious player,” he said on Nine’s coverage.

With the score sitting at 3-3 in the fourth set, Mensik made his move by breaking the serve of Ruud to lead 4-3. He then stayed composed to win the set 6-4.

Mensik raised both hands in the air after the win as the crowd roared in appreciation.

“He’s here to stay … what a game he has, it’s a frightening game,” Fitzgerald said.

“I just love seeing young players play, it warms my heart … it’s just enlightening for me to see them come.”

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The result makes it the first time since 2006 that two teenage players have beaten top 10 players at a major. Those two back then were Novak Djokovic and Andy Murray.

Mensik’s win against Ruud also makes it his fifth win against top 10 players.

The world No.48 was modest when revealing his secret behind such success.

“I’m just happy I have the opportunity to play against these players and am trying to enjoy every moment on the court. When I’m enjoying myself on the court, that’s the key and when I’m playing my best tennis,” Mensik said post-match.