Big picture
Sri Lanka's batting order has one more chance this series. In both matches so far, they appeared barely competent - they were unable to hit enough boundaries, frequently struggled to rotate the strike, and often found the opposition's spinners difficult to negotiate. On tracks they are supposed to be familiar with, Sri Lanka have batted as if they are the visiting team. Across the two matches, they have not managed a single top-flight T20 innings between the lot of them. Dinesh Chandimal's 66 off 54 was a substantial knock, sure, but it required a host of batters playing more aggressively around him for it to have contributed to a team victory; it wasn't a fantastic innings in isolation.
For South Africa, this is essentially a pre-World-Cup training run. The series now won, they may be tempted to give their wider squad a run in this match. They will perhaps be pleased, too, if the pitch is another big turner, because it is possible that towards the end of the World Cup, the UAE will throw up such surfaces.
South Africa's batters have proved through the course of this tour that they can not only play the turning ball, but that they are adept at finding boundaries against the spinners, and are not daunted by mystery spin. Their quicks have developed excellent strategies on slow pitches too.
Form guide
Sri Lanka LLWWL (completed matches, most recent first)
South Africa WWWWW
In the spotlight
He's the vice-captain, he bowls handy offspin, and is a demon at slip, but is Dhananjaya de Silva worth his place in this T20 team? After 21 T20I innings, his strike rate is a woeful 109.01. He played two good innings against a severely depleted India side in July, but in neither of those innings was he required to score quickly. If he gets another game, he could do with an explosive innings.
With all of 12 T20Is on his CV, Bjorn Fortuin is possibly bowling himself into a place in South Africa's best World Cup XI. He's opened the bowling in both matches, and done so well to keep the Sri Lanka opening batters quiet. In the second match, he not only took two wickets, he also went at just three runs an over - the most economical bowler in the match. Being a left-arm spinner he may have to now compete for his place with Keshav Maharaj, who has also been impressive. Another good spell, particularly in the Powerplay, could make his place safe, though.
Team news
Sri Lanka may think about dropping Bhanuka Rajapaksa, and bring Avishka Fernando back. They desperately need firepower in the middle order too, so perhaps Kamindu Mendis could get a game as well.
Sri Lanka (possible): 1 Avishka Fernando, 2 Kusal Perera (wk), 3 Dinesh Chandimal, 4 Dhananjaya de Silva, 5 Kamindu Mendis, 6 Dasun Shanaka (capt), 7 Wanindu Hasaranga, 8 Chamika Karunaratne, 9 Dushmantha Chameera, 10 Maheesh Theekshana, 11 Praveen Jayawickrama
South Africa are free to experiment now. Perhaps they'll rest Kagiso Rabada and bring Wiaan Mulder in.
South Africa (possible): 1 Quinton de Kock (wk), 2 Reeza Hendricks, 3 Aiden Markram, 4 Heinrich Klaasen, 5 Rassie van der Dussen, 6 Dwaine Pretorius, 7 Wiaan Mulder, 8 Keshav Maharaj (capt), 9 Bjorn Fortuin, 10 Anrich Nortje, 11 Tabraiz Shamsi
Pitch and conditions
It's a Khettarama surface at the end of a tour - it's probably going to turn. As there is often rain around in the evenings, an interruption or two is also possible.
Stats and trivia
South Africa have now won six T20Is in a row - two each against Sri Lanka, Ireland, and West Indies.
Tabraiz Shamsi needs one more wicket to get to 50 in T20 internationals. If he does it in this next match - his 42nd - he'll be the third-fastest South Africa bowler to the milestone, behind Imran Tahir, who did it in 31, and Roelof van der Merwe (who also played for Netherlands), who did it in 40.
Sri Lanka have lost their last five matches against South Africa, last winning in August 2018.