Tennis star Stefanos Tsitsipas played a hilarious prank on Nick Kyrgios on his 25th birthday when he posted his phone number online.

The pair share a special camaraderie after they became friends while on tour, especially after Kyrgios defended Tsitsipas when the Greek star was scrutinised after an outburst during Australia’s ATP clash against Greece in January this year.

Tsitsipas appeared on Instagram with an image of himself holding a cardboard sign captioned “Lift others up” with a phone number featuring an Australian code.

Fans realised that it was Kyrgios’ number and the Greek Australian star commented: “You are an absolute idiot, everyone stop calling me!!!!!”

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Kyrgios was overwhelmed by the calls: “What’s up guys, I understand it’s my 25th birthday, but please I understand that Tsitsipas posted my number on his Instagram,” he said on his Instagram story. “Please stop calling me, I can’t even play music, can’t do anything. Please stop calling my cell phone.”