The fourth-fastest serve in the women's draw at the Australian Open was delivered by a young woman who is partly powered by Hainanese chicken rice. Well, her mum taught her how to cook it. And, she adds with a grin, roast pork rice as well.

Her name is Astra Sharma and she's half-Indian, half-Chinese and fully talented. She's an Australian citizen, was born and raised in Singapore, speaks Singlish now and then at home, and is an athletic resident of the tennis court.

And at this Open, this amiable 23-year-old child of a former artillery officer is, well, firing nicely.

On Saturday (Jan 26), she and Australian partner John-Patrick Smith will play third seeds Barbora Krejcikova and American Rajeev Ram in the mixed doubles final. In her very first Slam, she is in a Grand Slam final. It's a long way for a Tampines girl born at East Shore Hospital.

"I'm speechless," she said later. "I had zero expectations and now I'm absolutely over the moon." Sharma didn't even think she was playing in the mixed doubles and now the Perth player is earning headlines in The West Australian newspaper.

Sharma praised her partner Smith, saying, "JP sees and reads the court so well", and he, at 30, the more experienced player, repaid the compliment, saying: "She's fearless, she goes for her shots and goes for her serves."

During the final on Saturday, her mother, Susan Tan, who was a student sprinter from St Theresa's Convent, will be courtside, but her father, Devdutt, a semi-retired acoustic engineer, will be in Singapore.

He's a former high jumper, a Raffles Institution boy and National University of Singapore graduate, who left Singapore in 2005, not because he foresaw a life in sport for his kids, but because he wished a different life for his family that also includes son Ashwin and daughter Tara.

Astra played football, chose tennis and studied at Vanderbilt University in Tennessee, where she still trains with coach Geoff McDonald. She's 23, the world No. 230 and has taken a step at the Open which surprised even her parents.

As Devdutt said: "This was a big shift, to the next level, and I didn't foresee it." Added Susan: "It's a little surprising but I also know her abilities and what she's capable of doing. It was a question of whether she could carry it off."

Sharma swept through the Australian Open singles qualifying, dismissing Vera Zvonareva, Varvara Flink and finally Irina Khromacheva 12-10 in the third tie-breaker.

In the main draw, she beat Priscilla Hon in 129 sweaty, scorching minutes, then lost to the talented Greek Maria Sakkari, but has since rolled through the mixed doubles without dropping a set.

It's only her first experience at a Major, walking the corridors littered with greats, adjusting to the noise and enormity of it, and it has been - as she told The Straits Times - a great education.

"I think that my 'B' game, if that makes sense, is good enough. I don't have to play bigger, I don't have to do more on a bigger stage, I can just play my game, I'm good enough to play with these (tour) girls."

Today, of course, she will be nervous, as she was initially before her semi-final when she walked onto Rod Laver Arena for the first time. Lanky - she is 178cm - and well-spoken, she grinned and said: "I was shaking in my boots."

She doesn't have experience, but she seems to enjoy the occasion and as her mother said: "She's mentally very tough, she just goes on and on and on."

And of course, she has the serve. That fourth-fastest one, by the way, was at 191kmh. Same speed as Serena Williams' fastest at this Open. But let's not to be too surprised. Astra, after all, means weapon.