Don't leave the dressingroom without Sune Luus. You won't see that written in as many words in South Africa's gameplan. Maybe because it has become a self-evident truth.

Before Sunday, South Africa had played 169 T20Is from Luus' debut against Bangladesh in Dhaka in September 2012. She was part of the side in 145 of them. That's 85.80%.

Of their previous five Luusless T20Is going into Sunday's T20 World Cup match against India at Old Trafford, South Africa lost four. Overall, they have lost 14 and won nine when she hasn't been around. When she has been in the XI, South Africa have won 73 and lost 67.

In short, Luus is good for business. Usually, that is. Only Laura Wolvaardt scored more runs in the home T20I series against India in April. Only Wolvaardt made more than Luus' two half-centuries.

But Luus scored six runs and survived for 10 balls in her two innings at the T20 World Cup. South Africa were hammered by 65 runs in the first of those matches, against Australia at Old Trafford on June 13. They squeaked to a two-wicket win, over Pakistan at Edgbaston on Wednesday despite chasing a modest 127. Another loss and their bid for a place in the semifinals would be on the rocks.

Something had to give on Sunday, and it was Luus. Along with Kayla Reyneke, who was out for a duck against the Aussies and for two against Pakistan.

Dane van Niekerk stepped into the latter vacancy to play her first game of the tournament and only her ninth international in either white-ball code since rescinding, in December, her retirement of more than four years. Van Niekerk is finding her way back into the team. Reyneke is 20 and at the start of an international career that will surely grow exponentially.

Luus is 10 years older, a former South Africa captain, a stalwart of exactly 300 internationals across the formats, and one of a fine team's best players.

Leaving her out requires a leap of faith. Mandla Mashimbyi took that leap. And was rewarded with a rousing six-wicket victory, thanks largely to the righteous rage of Marizanne Kapp.

Kapp suffocated the Indians' momentum by cleanbowling a scooping Smriti Mandhana with the 18th ball of the match and fooling - by way of a slower delivery - Richa Ghosh to send a catch looping to short fine leg with five balls left in the innings. Then Kapp took guard at 25/2 in the sixth, and with queenpin Laura Wolvaardt among the dismissed, to play the most consequential innings of her T20I career and guide South Africa to victory with five deliveries to spare.

Kapp's 45-ball 81 not out, which featured a stand of 97 off 63 with Tazmin Brits, was the difference between winning and losing. Or the difference between staying rudely alive in the tournament and marking time through the coming games against the Netherlands in Bristol on Thursday and Bangladesh at Lord's on Sunday, and then limping home along with the other first-round casualties.

That fate hovers still. Because, despite Kapp's heroics, South Africa remain one loss away from likely elimination. But somehow the alarm isn't ringing anything like as loudly as before. Call it what happens when a star player dazzles.

Of course it isn't that simple. Like Luus, Kapp was also part of South Africa's struggles against Australia and Pakistan. She did her bit with the ball in those games, taking 1/29 and 3/23. But she was out for 12 and 10.

Also like Luus, Kapp is central to her team's fortunes. She has played in 123 of South Africa's 183 T20Is since her debut against Australia in Taunton in June 2009. That's 67.21%. Kapp has been part of 63 wins and 55 losses in the format. Of the 60 T20Is South Africa have played without Kapp from her first, they have won 22 and lost 36. Kapp, too, is good for business.

While she is as demure off the field as she is aggressive on it, Luus is the opposite. Luus brings a kind of deceptive lithe languidness to the middle that seems at odds with the sternness she sometimes shows beyond the boundary. She probably picked up that trait during her 69 matches as captain - no doubt because she was trying to step into the giant shoes vacated by Van Niekerk. And was thus doubted accordingly.

Because of their differing roles, fitting Luus and Kapp into the same XI isn't often difficult. That's happened 173 times in T20Is. Surprisingly, there isn't much daylight between the results in those games: South Africa have won 85 and lost 82.

But turn the equation around and the value of Luus' ice and Kapp's fire is starkly apparent. Both have been missing in 18 skyexchange cricket. And South Africa have won only one of them. Best you don't leave the dressingroom without Luus as well as Kapp. Truths don't come more self-evident than that.

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