South Africa hammered Sri Lanka by 10 wickets despite Dimuth Karunaratne's battling hundred to seal a 2-0 series win inside three days in Johannesburg.

Karunaratne was unbeaten on 91 at the close of day two of the second Test with Sri Lanka beginning Tuesday's play at 150-4, but any momentum quickly subsided in a sorry collapse.

The tourists added just 61 more runs and lost their final six wickets for the return of a measly 35, setting the Proteas a meagre target of 67, as Anrich Nortje (2-64), Lungi Ngidi (4-44) and Lutho Sipam (3-40) produced devastating spells with the ball.

Dean Elgar (31) and Aiden Markram (36) steered South Africa over the line with ease in just 13 overs either side of the lunch break to complete a convincing victory.

Karunaratne (103) hit successive fours in the third over of the day as he aimed to help Sri Lanka to a competitive total.

But, having already threatened a couple of times, Nortje (2-64) eventually got the Sri Lanka skipper, his wicked delivery edged into the hands of Wiaan Mulder.

Karunaratne's overnight partner Niroshan Dickwella (36) soon followed, falling to the impressive Ngidi, and the remaining wickets tumbled quickly after that.

Mulder (1-52) dismissed Dasun Shanaka (8), while Sipamla swept up the lower order by taking out Wanindu Hasaranga (16), Dushmantha Chameera (0) and Asitha Fernando (0).

Markram and Elgar, whose first-innings 127 was the highest score of the Test, returned to the crease in a professional mood and hit nine boundaries between them.

The former did have a brief scare when Kusal Mendis appeared to catch him low before the boundary, but the third umpire ruled it not out after replays suggested he grounded the ball, and from there it was plain sailing for the hosts.

Dimuth Karunaratne holds the key to Sri Lanka salvaging the second Test with South Africa as the tourists reached 150-4 at stumps on day two - a second-innings lead of just five runs.

Having collapsed to 157 all out in their first innings, Sri Lanka saw Dean Elgar and Rassie van der Dussen build on their overnight stand of 114.

The pair added another 70, Elgar registering his 13th Test century and Van der Dussen eventually dismissed for 67.

But a maiden five-wicket haul in Tests from left-arm seamer Vishwa Fernando (5-101) in Johannesburg saw the Proteas collapse from 218-1 to 302 all out, denting their hopes of closing out a 2-0 series win.

A heavy defeat still looked the most likely outcome for Sri Lanka when Kusal Perera fell in the third over of their second innings.

Yet captain Karunaratne counter-attacked in thrilling fashion to post 91 at the close and ensure this side hold a slim advantage with six wickets still in hand.

Elgar knocked a Vishwa delivery past point to bring up three figures and at that moment there was little sign of the chaos to follow, with Van der Dussen easing to a half-century.

The opener eventually edged Dushmantha Chameera to first slip as his innings was ended on 127. Van der Dussen followed in short order, deemed to have gloved Dasun Shanaka behind on review.

Lungi Ngidi (3-26) went round the wicket to remove Perera, the seamer going on to account for Lahiru Thirimanne (31) and Kusal Mendis (0).

However, Sri Lanka - who lost Minod Bhanuka to a stunning Keshav Maharaj catch off first-innings tormenter Anrich Nortje - found hope at the top of the innings in the form of Karunaratne, whose 116-ball stay at the crease has so far yielded 17 fours.

Sri Lanka have little room left for error, though, and will hope the skipper and Niroshan Dickwella (18 not out) can guide them towards a total that Vishwa and an on-form attack at least have a chance of defending.

Moeen Ali has tested positive for coronavirus upon arrival in Sri Lanka, the England and Wales Cricket Board (ECB) has announced.

Ali and the rest of the England Test squad were checked at the airport in Hambantota on Sunday after flying in ahead of the two-match series, which gets underway on January 14.

The all-rounder will now observe a 10-day period of self-isolation, while team-mate Chris Woakes will isolate for a minimum of seven days after being deemed a possible close contact.

Further testing of the rest of the party will be carried out on Tuesday, with England's players then due to begin training the following day.

"Ali will now observe a period of 10-days self-isolation, in accordance with the Sri Lanka government's protocol on quarantine," a statement from the ECB read.

"Chris Woakes has been deemed as a possible close contact, and he will observe a period of self-isolation and further testing.

"The touring party will be PCR tested for a second time on Tuesday morning. At this stage, the team will train for the first time on Wednesday."

England selected a 16-man squad for the series in Sri Lanka, though seven reserves were also announced for the trip to help cover for potential absences.

The white-ball tour to South Africa in December was cut short due to a number of COVID-19 cases within the bubble shared by the two teams.

While the three-match Twenty20 series against the Proteas was completed, the one-day games scheduled had to be cancelled.

Anrich Nortje claimed career-best bowling figures as South Africa dominated the opening day of the second Test against depleted Sri Lanka in Johannesburg.

Nortje finished with 6-56 as the tourists were dismissed for 157 in just 40.3 overs, with the Proteas already closing in on that below-par total as they were on 148-1 in reply by the close.

Dean Elgar finished up unbeaten on 92, in the process becoming just the 10th South Africa batsman to reach 4,000 Test runs.

The left-handed opener combined with Rassie van der Dussen – who will resume on Monday on 40 not out – to share in an unbroken second-wicket stand worth 114.

Sri Lanka handed debuts to Minod Bhanuka and Asitha Fernando as injuries forced changes to the team that had lost the series opener by an innings at Centurion.

Kusal Perera top scored with 60 from 67 deliveries in their innings but, having made it to 71-1, his dismissal sparked a collapse, a middle order missing Dhananjaya de Silva and Dinesh Chandimal – who both scored half-centuries in the first Test – crumbling.

The visitors lost their final nine wickets for just 86 runs, the impressive Nortje rattling through the tail to claim his second five-wicket haul in the format.

Wiaan Mulder ended the innings with 3-25, including taking two in an over, while the other wicket was picked up by Lutho Sipamla. Despite being passed fit following a groin injury, Kagiso Rabada was not recalled to the team.

Fernando claimed his first Test wicket when Aiden Markram was caught at second slip for five, though that was the solitary success for Sri Lanka's new-look attack.

Elgar hit 16 boundaries to close in on a 13th Test century; he will no doubt be eager to get there on day two, having been dismissed for 95 in the previous match.