The 23-year-old will play the winner of the quarter-final between Russian Daniil Medvedev and Canadian Felix Auger-Aliassime later on Wednesday.
With Melbourne’s big Greek population, Tsitsipas has always drawn strong support at the Australian Open and it was the same again in the clash against Sinner.
“I think my humility helped a lot today. I knew I was going on the court facing a very good player. I tried to focus on my best shots and it paid off more than I thought,” he said in his on-court interview.
“Once again, stepping on to that court, having the crowd support, it is truly unbelievable.”

A finalist at Roland Garros last year, Tsitsipas was troubled by elbow problems at the end of last season and was concerned he might not be able to play in Australia.
“I am pretty sure my doctor is watching right now. He has been sending me texts after every single game,” he said.
“He said ‘I don’t expect to see you playing in Australia’. But I proved him wrong. I am happy I have found the right man to bring me back even stronger.”