Sri Lanka 338 (de Silva 60, Maharaj 9-129) and 151 for 3 (Gunathilaka 61, Karunaratne 59*, Maharaj 2-90) lead South Africa 124 (du Plessis 48, Akila 5-52, Dilruwan 4-40) by 365 runs

Think Galle, and now think of how things could have become more galling for South Africa. That's what happened on the second day at the SSC, where Sri Lanka took significant strides towards a series win.

South Africa succumbed to their second-lowest total in Sri Lanka, a mere seven days after they had slumped to their lowest on the island, to concede a first-innings lead of 214 runs. Sri Lanka's spinners ripped through them for a third time, with Akila Dananjaya picking up his second five-wicket haul in his third Test. Akila had a day to remember, after also notching up a career-best undefeated 43 to help Sri Lanka swell their first-innings total to 338.

Already that seems like enough, but with three days left in the match, Sri Lanka will look to pile it on, having chosen not to enforce the follow-on, against a wearing attack. Dale Steyn remains a wicket away from overtaking Shaun Pollock as South Africa's leading Test bowler, but delivered four overs without success, bowling third change. Lungi Ngidi, who left the field in Sri Lanka's first innings after being pinged on the shin when he dropped a return catch offered by Akila in his follow-through, returned during the second innings but only bowled fourth change, forcing Faf du Plessis to use part-timers Aiden Markram and Theunis de Bruyn. Kagiso Rabada shared the new ball with Keshav Maharaj, the only bowler to make some incisions.

Maharaj's first innings nine-for surpassed Allan Donald's 8 for 71 in Harare in 1995 as the best figures by a South African bowler away from home and second-best figures by a South African in an innings, anywhere. He picked up two second-innings wickets, putting him just two behind Makhaya Ntini's 13 scalps, the most in a match by a South African, but his efforts are unlikely to save South Africa.

So far in this series, the visiting batsmen have lasted 54.3, 28.5 and 34.5 overs - a total of 118.1 overs - the equivalent of under four sessions in three innings. They have scored fewer runs in total, 323 in three innings, than Sri Lanka's top-scorer Dimuth Karunaratne, who is unbeaten on 59, with 329 runs in the series and counting.

South Africa's approach against spin continues to be muddled and they have failed to answer the most pressing questions about batting on the subcontinent. Should they play for the turn, or not? Should they sweep, or not? Should they defend, or not?

Some of them, clearly, cannot trust their defence. Like Dean Elgar. He blocked the first three balls he faced, from Dilruwan Perera, and then went forward to dead-bat a fourth but Akila got the ball to dip, spin away and take the edge. Dhananjaya de Silva took a good, low catch at second slip.

Others are unsure what the ball is doing out of the hand. Like Theunis de Bruyn, who was included as a seventh specialist batsman and moved to No.3. He played for turn to an Akila ball that went on straight and was caught behind. Or Aiden Markram. He was trapped lbw, also playing for turn against Rangana Herath.

Sri Lanka's veteran only took one wicket in South Africa's first innings, though he could have had two, Hashim Amla dropped off him when he drove to short cover only for Danushka Gunathilaka to fluff the chance. Instead, Amla became only the third South African to reach 9,000 Test runs. That number will receive its dues in years to come. For now, South Africa need him to play like a man with 9,000 runs to his name and that did not happen.

Amla showed some signs of regaining form in a 55-run stand with du Plessis which was also the second-highest partnership South Africa have posted all series, but it was du Plessis who looked in control. The captain showed intent immediately after lunch when he struck five boundaries in six balls, and needed support. Amla could not provide it when he inside-edged onto his pad to offer short leg a catch and start the procession.

Then the sweep came into play. Du Plessis prospered and perished by the shot, eventually bottom-edging a Dilruwan delivery that was confirmed to have made contact with the bat on review. Temba Bavuma and Quinton de Kock were both confident on the sweep, but by then, South Africa's troubles were too deep.

Bavuma chipped a catch to short leg, Maharaj top-edged a sweep to square leg and de Kock was pinned on the front pad to give Akila his fifth.

After all that, South Africa had to take the field again and looked as though they wanted to be anywhere but in Colombo. A flat first 18 overs allowed Sri Lanka's openers to race to 91 without loss, with Gunathilaka scoring a second half-century in the Test before holing out to deep midwicket. In his next over, Maharaj successfully reviewed an lbw appeal against de Silva and the only other wicket fell when Kusal Mendis was run out. Karunaratne remains in control and with Elgar extracting sharp turn in the final over of the day, it seems only one result can be achieved.