Greek tennis star Stefanos Tsitsipas has made an astonishing pledge to build a school in Victoria if he wins the Australian Open on Sunday.

The World No.4 has been vocal about his love for Australia throughout the tournament, even using some Aussie slang - much to the delight of the spectators at Melbourne Park.

Following his 6-3 7-6 (2) 6-4 win over Jiri Lehecka in the quarter-finals on Tuesday, the Greek explained that he'd like to help Australian kids. 

'When it comes to charity ... I'd love one day, hopefully winning the Aussie Open and giving a portion of the prizemoney to build a school in Victoria, which is the state of education. I'd like to do that,' he told interviewer Jim Courier.

'Let's put tennis on the side because there are much more important things in life, I believe,' he said.

'I saw that Victoria is the state of education. There's an idea for me over there, that came to my mind.

'I've seen how difficult it is for a lot of kids around the world to go to school and get a proper education, which is important, because you know not all kids grow up privileged

'I would really like to give an opportunity to kids here in this state to build a school and provide them with free education, and anything else.

'And to put it into words – that's what Australia means to me.'

There is a strong Greek community living in Melbourne and many have turned out to support Tsitsipas on his quest for a maiden grand slam at the Australian Open.

Tsitsipas has mentioned he'd like to move down under at some point, and during his post-match interview expressed his admiration for Aussie actress Margot Robbie.

'Australia is such a great country, I like a lot of Aussie things,' he told Jim Courier during his on-court interview after booking a semi-final berth in Melbourne for the fourth time in the last five years.

'One of my favourite actresses comes from Australia, Margot Robbie.'

When asked whether he was 'pitching' himself to the Hollywood star, Tsitsipas replied: 'It would be nice to see her over there one day', while gesturing towards the stands at the Rod Laver Arena.

'Are you officially extending an invitation to Margot Robbie? I just want to be crystal clear here,' the four-time Grand Slam winner continued.

Tsitsipas' answer was as succinct as it was eloquent, as he replied: 'Absolutely'.

By beating Lehecka, Tsitsipas maintained his unbeaten record in Grand Slam quarter-finals with six wins in six matches.

The Greek, who along with Novak Djokovic still has a chance of finishing the tournament as the world number one, will take on Karen Khachanov in the semi-finals on Friday.