Proteas: PLEASE get those 5 runs, Theunis!

Cape Town - Would just five more runs be too much to ask for?

Put in the context of South Africa's ongoing, rank batting frailty in the Test series in Sri Lanka, it might yet prove elusive.  

But Theunis de Bruyn reaching his half-century on Monday's day four of the second clash in Colombo, from an overnight 45 not out, would mark a maiden milestone for the right-hander in his sixth Test for the Proteas.

In an on-and-off career at this level so far, the 25-year-old came closest to a 50 in the first innings of his second Test match against England at Lord’s last year, but was dismissed by James Anderson for 48.

But there is another key reason, from a team perspective, why posting a half-ton - at very least - would provide some semblance of relief to the embattled tourists.

That is because they are at novel risk in the modern era of failing to register a single half-century between them in a completed series.

Defeat in the second Test, for a Sri Lankan clean sweep of the series, still seems a 99 percent likelihood for Faf du Plessis' team, as they closed day three on 139 for five, still a monstrous 351 runs short of their victory target of 490.

But De Bruyn, very much a fringe player for some time, has already seen off more deliveries (97) in his fighting knock than any compatriot in a single vigil in the series so far, so pretty much deserves to reach his fifty on that basis alone.

Skipper Du Plessis faced 88 balls in top-scoring for SA with 49 in the first Test at Galle, and also notched a 51-ball innings of 48 in the first knock of the current contest, but De Bruyn has the opportunity on Monday to mercifully be the first to raise his bat for a half-century.

South Africa had an almost as disastrous Subcontinent tour - of India - in 2015 from a batting perspective, the four Tests on that occasion seeing only AB de Villiers (now retired) manage to get to or beyond 50; he did it twice.

Although it will be hoped that De Bruyn - who still has possible, meaningful assistance from Temba Bavuma (14 not out) and Quinton de Kock before the Proteas have to send in their tail-end trio of fast bowlers - can hold the fort for considerably longer yet, he has already strengthened his claims through this innings for a more regular run of appearances in the Test side during the looming home summer.

Amidst the general climate of gloom around SA's specialist batting, he earned a significant laurel during Sunday’s play from Russel Arnold, the television commentator and former Sri Lankan international.

The 44-Test batsman described De Bruyn as "the only South African batsman who seems to be picking the deliveries (from the Sri Lankan spinners)".

At worst, and given the renewed general SA angst about facing top-notch spinners in Asian conditions, De Bruyn seems an attractive proposition for the next time the Proteas visit the Subcontinent for Tests - another series against India in just over a year's time, marking their introduction to the newly-established ICC World Test Championship.

*Follow our chief writer on Twitter: @RobHouwing