Kyrgios serves Djokovic off the court

Nick Kyrgios has delivered a serving masterclass to upset Novak Djokovic and storm into the semifinals of the ATP tournament in Acapulco.

Kyrgios was untouchable on serve, crunching 25 aces in just two sets to send the top seed and 12-time Grand Slam champion crashing out in a 7-6(9) 7-5 quarterfinal boilover.

Apart from reaching his second ATP semifinal in as many weeks, Kyrgios’s victory completes a rare set of wins over tennis’s Grand Slam titans.

The Australian had already conquered fellow major winners Roger Federer, Rafael Nadal and Stan Wawrinka.

And at just 21, Kyrgios is the youngest player to have snared these big scalps.

The world No.17 announced his arrival on the world stage with a thunderous win over Nadal in 2014 on Wimbledon’s grasscourts before beating Federer on clay in Madrid, then Wawrinka on a hardcourt in Montreal.

Next up for Kyrgios is another big server in unseeded American Sam Querrey, who earlier on Thursday took out fourth-seeded Dominic Thiem 6-1 7-5.

The other semifinal will feature two-time champion and second seed Nadal against third seed Marin Cilic.

Nadal extended his winning streak in Acapulco to 13 matches with a 7-6(2) 6-3 defeat of Yoshihito Nishioka.

Cilic cruised into the last four without picking up a racquet after American Steve Johnson withdrew because of a right ankle injury.