MELBOURNE - Tennis through the year is preoccupied by a predictable range of subjects. Geography, for instance. Where are all the Swedes, we wonder? They won 24 grand slam singles titles between 1974 and 1992 and only one since then and at the Australian Open there is only a single fellow in the men's draw.

What happened to the tall invasion? An army of 1.98m giants, we once decided, was going to launch a coup but it turned out to be a myth. Though it's a nice touch that the 2.11m Ivo Karlovic's father is a meteorologist. Who else knows the weather up there?

Heat, of course, causes some annual Aussie angst. Players wobble, shoes stick, ice bags become a favourite accessory and Roger Federer plays at night. Well, so far at least. Nevertheless camps have been dutifully formed: some will complain about the heat, others will complain about the whiners and some are just happy to play.

Petra Martic and Luksika Kumkhum, world Nos. 81 and 124 respectively, who might not usually be found on Rod Laver Arena, somewhat caught fire in the midday sun: 62 winners, 13 breaks of serve and a third set that went a dramatic hour. Martic won 6-3, 3-6, 7-5 and who says we only require stars for tennis to display its spirit?

Have I seen hotter years at the Open? Unquestionably. Would I like to run short sprints in this heat, which feels like being wrapped in a blanket? Nope. When I asked the charming Luksika about the conditions, she smiled: "I'm from Thailand, but it was still hot for me today."

Sport has always asked uncomfortable questions in disagreeable conditions and I grew up hearing about Indian Davis Cup players who had to wrap themselves in blankets at changeovers during chilly ties in the old Soviet Union. Tennis must always investigate fitness and resolve - find your best on the worst of days - yet not turn an essentially skilful game into an Ironman contest.

Martic described the conditions as "ugly" and when told that Garbine Muguruza had said she had blisters because of the surface heat coming through her shoe, she added, "I also got some blisters and I took painkillers after the second set". And yet she explained: "You just need to be mentally tough and ready to just suffer out there and try to make it through."

And finally, as an eternal subject, there's always age. Tennis, like most games, is besotted with the new and the old, dazzled by the young who dare to emerge and respectful of the enduring player who refuses to leave. Both, in their own ways, are acts of defiance.

Federer, born in 1981, is as dated as Raiders Of The Lost Ark and Karlovic, a month from 39, is as ancient as Life On Earth (well, the series by David Attenborough). Still, in the first few days of the Open the finest story was someone less than half their age. Marta Kostyuk, the 15-year-old from Ukraine, is the youngest to reach the third round at Melbourne since Hingis in 1996. Martina's subsequent journey went well, Marta's we shall see.

Kostyuk, a qualifier who defeated the 25th seed Peng Shuai 6-2, 6-2 in the first round, finally lost on Friday to Elina Svitolina 2-6, 2-6. A new talent had met an old hand. When asked later what she learnt, Kostyuk's reply was as nonchalant as her backhand return winner on the second point of the match: "Well, a lot. How much you have to pay Svitolina to have one-hour lesson, so I got it for free."

Here was a kid on a wild ride, in a big court, amid a large crowd, against her compatriot ranked 517 places ahead of her, but she wasn't just happy to be there. She cried. "I didn't show even maybe 10 per cent of what I can," Kostyuk said later and it was the dissatisfaction with her little fairy tale which showed off her perfectionism.

Introductions in sport are delicious moments, a sudden explosion of raw talent, when the cameras are looking, by athletes too young to be properly scared yet. Interviews follow, attention arrives and as something is gained so is a little lost. Expectation inevitably erodes innocence. It is part of the pact.

Already Kostyuk has been called a "sensation" and for every Tiger Woods, Lionel Messi, Sachin Tendulkar, all brilliant studies in precocity, there are too many forgotten tales of young athletes who never grew into the labels we gave them. In all our excitement over the glimpse of a new talent it's best we remember that The Sure Thing and The Can't Miss are only figments of our over-heated imaginations.