Try this on your smart phone. Or, if you were born during the 20th Century, on a stop watch.

Click it on, then off so that half a second elapses. Not a full second. That's a luxury. Then imagine what you can meaningfully achieve in that time span.

Blink a couple of times quickly. Frame a thought, maybe two.

Or, if you're Chris Rogers watching Dale Steyn sprinting menacingly towards him with the hum of 15,000 blood-lusting fans in your ears and the scrutiny of a global television audience in your consciousness, you know you have that amount of time to focus on a rock hard, brand new 156 gram cricket ball launched at you and travelling a tick under 150km/h.

But seeing it is just the start. In the time it takes you and me to swivel our heads 90 degrees, Rogers will have a series of complex computations to perform to try and avoid the indignity of losing his wicket or the pain of getting hit.

Once he's sighted the ball as it leaves Steyn's hand, he must immediately judge its approximate point of pitch which, in turn, dictates whether his right foot and his body weight moves forward to meet it as close as possible to its bounce, or if his left foot should carry him back and therefore allow him to safely defend his wicket and his person.

If it's the latter, the decision is slightly more straightforward though no less crucial. Hit the ball, or get out of its path.

If – as is more likely with the first act of a Test match - it's the former, he must decide whether the heavily lacquered ball will swing in the air away from his bat towards where a cordon of fielders has been set up awaiting an edged catch, if it will curl back sharply and maybe painfully into his body, or simply carry straight on towards his stumps.

Or perhaps it will start to swing one way, land on the six rows of raised stitching that bind the ball's leather casing, and dart away in a different direction having dug into the lightly grassed but heavily compacted surface of the pitch.

Bear in mind that none of these contingencies will arise until the ball has reached the half of the 22-yard pitch closest to Rogers. That now gives him quarter of a second.

"There are some guys like (England's) James Anderson who you honestly don't know which way it's going to swing, and the changes in his bowling action or the way he holds the ball are so small that you've got no choice but to wait and see which way it's going," Rogers mused, fingers drumming lightly on his chest as he visualised what awaited come the opening ball of this much anticipated Australia-South Africa Test series. "The good thing is with a brand new ball it will often swing early once it's released …. so that gives you a bit more time." His voice trails off, as though he's trying to convince himself that really represents a bonus.

For Rogers, who has made a life in cricket putting himself in the firing line of the opposition's best and fastest bowlers when they're at their freshest and armed with a weapon at its highest calibre, the torment has started long before the first of what he hopes will be hundreds of those split-second decisions made throughout the course of a productive day.

At Test level, where the spotlight is harshest, the inadequacies in your game pinpointed and exploited most ruthlessly, and the repercussions of failure most extreme, it's the evening before the game starts that the doubts can start to percolate.

"Maybe in my initial years when I started playing state cricket I would get a bit anxious, but I've never really been a nervous person until I started playing for Australia," Rogers said.

"That nervousness comes from the pressure to perform, to not let down your team or your country, and also because it just means so much.

"I'm sure I could speak for everyone who has played for Australia that the desire to stay in the side and to do well is all-consuming.

"It's difficult not to think about it and I've had sleepless nights as a result, but I try to switch off and think about anything other than cricket, which is hard to do.

"I think one of the better skills I have is to adapt when I'm out there – to read the conditions and to then play accordingly.

"Often there's a risk that you can play the game in your mind, do all your batting before you go out there and that can be detrimental."

It's that night before you've got an early flight and you don't sleep at all lest you sleep too long.

The final hours before an exam that will determine your career, perhaps shape your life. Except you don't know, when you get to the exam hall, whether the paper that falls from the envelope will contain the questions you've spent the year preparing for, or a slip that says simply 'come back tomorrow'.

That's because opening the batting for a cricket team is different to pretty much all other sports pursuits.

Golfers arrive knowing where and how they have to hit the first ball.

In tennis, it's a matter of whether you hit it first or try and hit it back.

Depending on how the coin lands, Rogers will have half an hour to prepare to face Steyn's fury, or alternatively contemplate a day or more standing in the field waiting for his examination to begin.

"Sometimes as an opener it's best to be bowling first," he admits with disarming candour.

"Day one of a Test match you assume (the pitch) is going to be a bit lively, there's going to be something in it.

"So a lot of the time you're secretly hoping (the coin) comes down so that you're bowling first, even though you know that's your job – to get out there and perform a role for the side and set a foundation for the other batsmen who are coming in behind you.

"Mentally you are ready to go. But often secretly you're hoping it's a fielding day."

Not that he'll be watching intently from the dressing room or be peering through the glasses he relies on for everyday wear – he swaps to contact lenses when batting - at the television to learn the result when skippers Michael Clarke and Graeme Smith meet for the ritual swapping of the team sheets and the flipping of the florin.

He'll wait for the crowd's response to alert him how it landed.

At that time, Rogers prefers to bury himself deep in the dressing room, comforting himself that he's done all the preparation possible to perform his job, focusing on the myriad indicators and elements that tell him all's well with his game, ensuring that he's as organised as possible to avoid a last-minute panic.

Not that he's a neat freak when occupying his own personal space within the Australian team's temporary office.

"A little bit of chaos doesn't go astray I think," he smiles.

"I've seen a lot of cricketers who have everything planned down to the last degree, but I sometimes wonder what happens when they're thrown a curve ball and how they might deal with that.

"I once heard Justin Langer (former Test opener who Rogers partnered many times at the top of the Western Australian order) say he was chasing perfection.

"And that didn't mean he was aiming to average 100.

"It was just being mentally in the same zone every time he went out to bat, and I think that's important."

The 36-year-old - who made his first-class debut last century and has since scored more than 21,000 runs at an average of pretty much 50 per outing – will have, however, prepared according to his well-worn routine. He will have asked the coaching staff to provide him with a short session of 'throw downs' – exactly as the name suggests – in the nets before the team begins its warm-up.

He won't bother inspecting the pitch because his colour blindness prevents him from ascertaining if its grass cover carries a green tinge or not.

If news filters back that he's batting, he'll fit some of his protective gear, file out with his teammates and stand distractedly if respectfully through the ceremony of the national anthems, then dash back to grab his gloves, batting helmet and opening partner David Warner.

The pair won't have spoken much in the lead-up to them walking out to battle.

"We've done our chatting," Rogers says of that time immediately prior to entering the arena, where the bowling team – outnumbering the batsmen more than five to one – is primed and waiting.

"Even though you have a real partnership as openers, that 10 or 15 minutes before you go out there is quite introverted.

"You are focusing on the challenge ahead."

There is but one certainty as the pair emerges on to the soft grass at Centurion and take the anxious walk to the centre.

That Rogers will face the first ball.

For all his extroverted and high-octane bravado, Warner prefers to watch the opening delivery from the other end.

It's a simple choice that Rogers understands and respects. Langer always took the first ball in his long and productive Test union with Matthew Hayden.

"I do it every time, whereas when I opened with Watto (Shane Watson) he wanted to take first ball every innings," Rogers explains.

"But the longer you open, the more you realise that you can't hide from it. If the other guy doesn't want to do it then you have to be ready to do it.

"If I had a choice, I would probably prefer that we alternate - but I know personally that I don't want to hide from it.

"It's your first challenge. You know it's going to be tough, so you can't shy away from that."

He'll scratch his guard into the unmarked crease line.

Rogers was here, carved into the turf with his shoe spikes.

He'll block out the din from the crowd, the chatter from the queue of lippy fielders arcing out behind him.

"It's just white noise, I don't buy into it," he says of the verbal 'gamesmanship'.

And then it's Steyn at the top of his run-up. A pitch length or further in the distance.

His all white clothing framed by a large white sightscreen. And hidden deep within his hand, a dark red ball. Not to be revealed to the batter until the last possible second. Or half second.

What goes through a batsman's mind as the bowler begins his sprint, the noise from the crowd soars, the world shrinks into an infinitely smaller orb that might deliver as many uncertainties within that split second as life itself

Fear of physical injury? Deeper fear of failure? Wrestling the instinctive urge to second-guess what's coming? Dread that it might be the searing yorker that Mitchell Johnson once landed to scatter Rogers' stumps the very first ball of a domestic one-day game, the first time he'd ever seen such a delivery attempted at the outset. Or hadn't, as it turned out.

Perhaps the desperate need to score that solitary run that somehow separates misfortune from abject failure?

"For the opener, there is no better feeling in cricket than getting off the mark," Rogers confesses.

But no. In most cases - certainly in the case of Chris Rogers - it's invariably something much more prosaic.

Far removed from the 'watch the ball, watch the ball' mantra that many a coach will drum into their charges to repeat as a silent chant as the bowler approaches.

"For me, during the Ashes series, I was just telling myself 'don’t get out during the song'," he laughs, a little self-consciously.

"The Barmy Army would always start the day singing 'Jerusalem', and I set myself to still be there once they’d finished singing it.

"It was just a little thing. It only went on for two, maybe three deliveries. But it was just a little bit of motivation, a little hurdle I could tell myself I had cleared.

"And that meant I had at least survived until then."

One and a half seconds gone. Six hours until the day’s work is done. With the next awaiting like a ticking stop watch.