Things are heating up at the Australian Open in Melbourne

Sun's out, guns out! Man works on his tan in the crowd of the Australian Open — but the woman sitting behind him looks less than impressed

The Australian Open is meant to be about the tennis stars but a few punters are stealing the limelight thanks to their daring clothing choices.

In one man's case, his lack of clothing caught everyone's attention as he sat in the stands without a shirt on the second day of the Open, taking advantage of the 35C heat in Melbourne on Tuesday afternoon.

But a woman sitting behind him did not look impressed with his choice.

Another man unable to decide which team to back opted instead to sport the flags of both Japan and Australia on his headpiece.

One spectator has removed his shirt during the first round matches at the Australian Open tennis championships, much to the annoyance of a nearby woman

Supporting Australia or Japan? Fans look on during day two of the 2017 Australian Open at Melbourne Park

Two Australian fans are also pictured sheltering themselves from the sun using a blanket and oversized novelty hat. 

Completing the look with yellow and green face-paint, they cheer for Lizette Cabrera of Australia during her first round match against Donna Vekic of Croatia. 

Other fans don the green and gold in support of the host nation. 

Some young tennis fans bring along an inflatable kangaroo, as they watch Alexander Zverev of Germany against Robin Haase of the Netherlands battle it out on court. 

Fans cheer Lizette Cabrera of Australia during her first round match against Donna Vekic of Croatia on day two of the 2017 Australian Open

Australian tennis fans are seen watching the match between Alexander Zverev of Germany against Robin Haase of the Netherlands

Japan's Naomi Osaka, right, signs autographs after winning her first round match against Thailand's Luksika Kumkhum

Of course the crowds could stay away from fan favourite Serena Williams, who is on her way to achieve her seventh Australian Open singles victory after beating Belinda Bencic of Switzerland.

'She's (Bencic) such a great player. She was just recently in the top 10 so she's been playing great,' Williams said courtside, the ABC reported.

'It was one of the toughest first-round matches I've played, so I knew I had to come out strong.'

Australia's Lizette Cabrera was beaten by Croatian Donna Vekic in her grand slam debut.

The 19-year-old Queenslander went down 7-5 6-2 on Tuesday to Vekic, who at No.99 is is nearly 100 spots above Cabrera in the world rankings.

Vekic's second-round opponent will be either former world No.1 Caroline Wozniacki from Denmark or another Australian wildcard, Arina Rodionova.

Serena Williams signs autographs for fans after winning her first round match against Belinda Bencic of Switzerland

Fans lean over in the hopes of getting a signature from Serena Williams after her win over Belinda Bencic at the Australian Open tennis championships