Dimuth Karunaratne has a hard time convincing people it is tough to open the batting in Sri Lanka. He tried this line once in a press conference overseas, and you could practically hear the eyerolls. Sri Lanka? The place where conventional seam bowling goes to die? Sri Lanka? Where pitches are so dusty that dismissed batsmen have to be blasted with industrial-strength firehoses before they are allowed back in the dressing room? The place where for 10 years Sanath Jayasuriya was like a tyrannosaurus rex, and opening bowlers the shivering, fear-struck, urinating goats he fed on.

Rain may have helped SL's rescue act - Shamsi The sharp shower just before scheduled tea worked to blunt South Africa in the third session, said left-arm wristspinner spinner Tabraiz Shamsi. South Africa had had the hosts 161 for 6 when a brief torrential downpour forced the teams to run off the field. Sri Lanka would eventually make 287 with the ninth and tenth-wicket stands adding 111. "I think after the rains came, the outfield was slightly damp," he said. "The ball got a bit softer. That might have played a part in Sri Lanka's recovery, but I don't want to take any credit away from the way the guys batted."Shamsi, who finished with 3 for 91 in the innings, said the track played just as South Africa expected. "Turn is something you expect when you come to Sri Lanka - the spinners have to do more damage than the seamers. All our seamers were brilliant. Kagiso Rabada took four wickets and he showed his class. Dale Steyn, Vernon Philander - they all chipped in with wickets. Keshav Maharaj also did a good job. We're really happy with the way it went in the first innings."

But Karunaratne is adamant. "I'm telling you, it's the toughest place," he said, in private, on another occasion. "Usually after a couple of overs, you can get a gauge on what the pitch is doing and whether the seamers or spinners are the bigger threat. Not there. Sometimes the spinner is on and the new ball is jumping from here. Then a seamer bowls and it's jumping from there. How to make sense of this? You have no idea what is going on."

It is easy to wonder if this is a roundabout defence of his Test average, which had long sat in the low 30s, and has only made a serious upward charge in the last 18 months. But it is not. Statistically, Sri Lanka is an opener's nightmare. Since 2014, the average opening stand in Sri Lanka is 26.31 - lower than for every other Test nation (save for Ireland, which has only had one Test).

So there he stood, about to play his 50th Test, with fewer than 3200 runs to his name and a batting average under 35, pleading with the world to stop judging him based on that CV, and just to let him show you the crap he has to deal with on an annual basis. Against, maybe, the best attack on the planet, that is exactly what he did.

Dimuth Karunaratne has become only the fourth Sri Lankan opener to carry his bat through a Test innings ESPNcricinfo Ltd

Vernon Philander got a little new-ball seam movement; Dale Steyn got reverse swing later on; Kagiso Rabada had the ball leaping off the pitch in all of his opening-day spells. In the face of all these varied threats, Karunaratne was Sri Lanka's most assured batsman. No one else even came close.

While all that was happening for the seamers, Tabraiz Shamsi was getting the ball to pounce off the surface as well, Keshav Maharaj turning a few of his own. Others tried to thwack the spinners out of the attack. Niroshan Dickwella played the sweep so often you wondered if he knew any other shots. Karunaratne was beaten by the spinners, but never into submission. If the ball fizzed past once, he got the middle of his bat to the next one.

It was at the end of the day, after Sri Lanka had lost 6 for 161 through the middle period, that it became really clear that a below-35 average doesn't do justice to this batsman. He shielded the last two batsmen from the toughest bowlers, turned down singles into the outfield early in the over, defused more reverse swing with the calm of a bomb technician working on a ticking suitcase, and manouvered balls between fielders when he wanted to keep the strike.

Dimuth Karunaratne became the third Sri Lankan batsman to score a century in his 50th Test match ESPNcricinfo Ltd

It is no surprise that his focus did not waver even after he got to his century - four of Karunaratne's eight hundreds have been 150-plus scores. But as good as this innings was, it was still nowhere near his best knock. In 2014, he had quelled Trent Boult and Tim Southee for 363 balls on a Christchurch deck with so much greenery, the pitch alone would have offset New Zealand's carbon emissions for the year. Then in 2017, he faced down Ravindra Jadeja and R Ashwin on an SSC track that crumbled so readily, the pitch was three feet underground by the time the match finished.

This was no breakout knock, just another rock in a bank of evidence to suggest that this is a very good batsman. So good, he even hooked Dale Steyn for six without actually meaning to. "I actually wanted to leave it, but I accidentally hit that one," he said after play. "When I was playing in Bangladesh for the A team last month (the tour was part of his rehabilitation following a finger fracture), I was batting really aggressively, so maybe that habit came to me. But I can't do that in future - in the next match I have to leave those bouncers."

If anyone refuses to believe what he had to put up with on Thursday, he need only point them to the scorecard. While Karunaratne made 158 not-out; the next-best score was 26. This time, at least, he shouldn't have much trouble convincing folks just how tough he had it.