South Africa v Sri Lanka, 3rd Test, Cape Town, 3rd day January 5, 2012

Smith the mathematician calculates victory

Having taken up the South African captaincy at a young age, Graeme Smith is now showing how he is putting his experience into practice

Graeme Smith had his tongue firmly in his cheek when he described his decision to accept the captaincy at the age of 22 as "stupid". Then, he had played just six matches and 25 ODIs and may have been seen as a boy accepting a man's job. Now, 89 Tests and 150 ODIs later, it is obvious that he has grown into an adult who understands his role better than most.

Although South Africa's bowlers did what Sri Lanka's couldn't at Newlands and ensured the series is now theirs to lose, Smith's role in managing them was vital to the team's success. Knowing they would probably have to bowl for the best part of two days, having taken to the field 40 minutes before tea yesterday, he had his work cut out and he went about it admirably.

He juggled his bowlers with the skill of a mathematician. Dale Steyn and Morne Morkel never bowled a spell of longer than four overs. Jacques Kallis, who had batted for more seven hours for his second double-century, was only brought on after tea, when he had rested for long enough to be able to crank it up to 139 kph. Imran Tahir finally got his chance to bowl for a prolonged period of time and with a cowering Sri Lankan line-up in front of him, was able to squeeze and assault at the same time.

The attack as a whole came to completion in the way they have been talked about since the start of the summer. As a unit, they operated like clockwork. The man pulling the strings, Smith, was the mechanism that kept the clock ticking.

Smith's major captaincy decision was to declare on the second day. Like their Australian counterparts in Sydney, individual milestones did not feature highly on South Africa's priority list

He started off with Steyn, who took a wicket in his first over, and had Morkel bowling with him. Tahir came on to function in tandem with the seamers. Until the last over before lunch, he had no success and simply did the holding job while Philander got rid of Samaraweera and Steyn returned for a second spell to take two wickets. Tahir completed the pre-break rout, leaving little to do after the break to force Sri Lanka to bat again.

Philander did what he does best by using a questioning line to create uncertainty and when Sri Lanka were nine down, Smith played an important hand. Knowing that Morkel is still battling to find his confidence, he gave him the ball and asked him to finish things off. Morkel obliged and the result would have given him a boost that can only be explained by understanding Morkel's personality and how his emotions play a role on his performance.

Choosing to enforce the follow-on was the obvious logical option but it would mean asking the bowlers to do an extended job. There was little to stop Smith from electing to bat again, relying on the top three or four to add a quick 150 to 200 runs and put the match out of Sri Lanka's reach, but Smith decided to turn the screws. In doing so, he also knew he would have to manage which way they turned.

Steyn and Philander opened the innings with short spells of two and three overs each. Once a wicket fell Morkel and Steyn then got a turn and Philander returned for another two overs. When that didn't work, Smith turned to Kallis and asked him to keep things going for a while. By then, Kallis was refreshed and ready and he bowled an aggressive seven over spell, took a wicket and opened the door for Smith to return to rotating his main three.

All the while, Tahir operated on the other side, finding turn out of the rough and dramatising every ball as if it were a five-act play. Philander said the quicks had the freedom to function in bursts but Tahir enjoyed a different type of freedom. He knew he would be able to occupy that end without interruption and had the space to ply his own trade.

Tahir has made no secret of his gratitude to Smith for showing faith in him and giving him opportunities. Smith's faith in Tahir is obvious, even when the legspinner fielded on the boundary, an aspect of his game he has spent time working on, Smith would applaud from slip. Before the summer, there were concerns about how Smith would handle an attacking spinner, having always captained a containing one, but so far he has done so impressively.

Smith's other major captaincy decision was the one to declare on the second day. He called time on the South African innings when he could have chosen to bat on and push the advantage. With 580 runs already on the board, the opportunity existed for them to seek well over 700 and let the Sri Lankans know that there was not even a sliver of a chance for them to get back into the match. In the process, AB de Villiers could have gone on to a double-hundred, Rudolph may have been able to record three figures and even Mark Boucher could have had an opportunity to chalk up some valuable runs.

Like their Australian counterparts in Sydney, individual milestones did not feature highly on South Africa's priority list. Time did. Smith knew that on a flat pitch, South Africa would need plenty of overs to work the Sri Lankan batsmen over and their quick scoring rate gave them enough of a cushion. As it turned out, the first innings did not even last long enough to need a second new-ball. The second innings may not need one either, with the new ball 27 overs away.

Even if they do need a new ball, South Africa are likely to walk away victorious, with their first series win at home since 2008. The victory will likely be attributed to everyone from Jacques Kallis to Vernon Philander. In the background, Smith will smile with satisfaction, knowing he had a big part to play as well. And he'll be right.

Firdose Moonda is ESPNcricinfo's South Africa correspondent