The hundred belatedly comes up as Sangakkara knocks a single to the cover sweeper. The Sri Lankan fans are loving it, though - flags are waved, drums are beaten and trumpets played after every run. But that's a nasty one from Mathews - he's hit on the glove by a lifter from Morkel and calls for the magic spray-wielding physio.

Back to pedestrian mode. Sangakkara has taken 71 balls to score 25.

Michael Vaughan
Ex-England captain on BBC Test Match Special

"Sri Lanka are still playing the waiting game, but South Africa have been excellent in the field and with the ball. You still feel that Kumar Sangakkara is setting himself. Sri Lanka have to go up the gears soon - they can't just hope that the last 10 overs will go for 100. Tahir has got them at the moment. Sri Lanka have to take that gamble soon."

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No sooner said than done. Mathews has a sighter from Tahir then launches a big blast over long-on - it's only four, inches away from being six.

Having strangled Sri Lanka with 12 unbroken overs of spin, South Africa turn back to the pace of the towering Morne Morkel. Sangakkara and Mathews are both sporting the new clip-on attachment to the back of their helmets which one of the leading helmet manufacturers has introduced for extra protection to the back and side of the neck, following the death of Phillip Hughes after he was struck there by a short ball last year. Patience is a virtue for the fifth-wicket pair here. The debate on TMS: does Sanga know what he's doing? When do they step up a gear?

Thanks, Michael. Plenty for Sri Lanka to ponder, then - but in captain Mathews they have a man for a crisis. It's not for nothing he has the best Test batting record as captain of all time, bar a certain Donald George Bradman.

Tahir bounces in for his sixth over, and just a couple of singles from it - the leggie has 2-18 from six overs.

Stephan Shemilt
BBC Sport in Sydney

"It was almost as if the significance of that Jayawardene wicket was lost on the crowd. There was no fanfare, no standing ovation. If that was his last international innings, it was low-key in every sense."

Halfway through and Sri Lanka are struggling here. They have limped to only 87-4. And that is it from me for a while, so time to leave you in the safe hands of Mark Mitchener. Enjoy.

A sad way to end for what may well be Mahela Jayawardene's finale.

It is time for Sri Lanka's big players to step up to make sure he can play one more match. And they have a lot of experience at the crease. Legendary batsman Kumar Sangakkara has been joined by his captain Angelo Mathews.

Andrew Samson
BBC Test Match Special statistician

"Following the dismissal today, Imran Tahir has now dismissed Mahela Jayawardene four times in ODIs, having bowled 34 balls to him and conceded 12 runs (average 3.00, strike rate 35.29)."

Image source, Getty Images

Vic Marks
Ex-England spinner on BBC Test Match Special

"Maybe it wasn't as short as Jayawardene thought - he tried to pull and hit it very tamely to the fielder. He certainly didn't make good contact, a tame ending and who knows whether this might be his last innings for Sri Lanka as he's given up Test cricket and is giving up ODIs at the end of this tournament. Tahir has bowled really well and batting has not been easy - South Africa have created pressure which has never been relieved."

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Well, Jayawardene's reprieve does not last long. A simple catch for Faf du Plessis at short mid-wicket from a misjudged pull shot and Sri Lanka are in all kinds of trouble. Remember, they won the toss and chose to bat first.

Scorecard

Image source, AP

It is great hearing the discussions between the umpires, which has only been brought in for the first time in this World Cup today. The projected impact is 'umpire's call' so Nigel Llong, who said the batsman was not out, does not have to change his decision.

Four singles then come from the 23rd over.

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Jonathan Agnew
BBC Test Match Special

"Tahir's very excitable. He's in that category of bowlers like that Pakistan opening bowler Sohail, who wants to review everything - as does Stuart Broad. He's quite a long way forward - but it did look as though it hit him outside the line, so well done umpire Llong."

Wonderful screaming from Imran Tahir. Who is absolutely convinced he has Jayawardene trapped lbw.

Vic Marks
Ex-England spinner on BBC Test Match Special

"Duminy was almost rushing to get through the over so much, that he's lost control and bowled two wides. This feels a bit like that World Twenty20 final where West Indies were about 38-2 after 10 overs, very cagey, and then went berserk and finished on 150 - and won."

Listen to Test Match Special commentary via the audio icon.

Sri Lanka need all the help they can get at the moment, so are grateful to a couple of wides from JP Duminy. Sri Lanka still have a lot of work to do to make this respectable.

Dennis Ethan: Come on you Sri Lankans. Got to listen to your national anthem for one more time.

Sri Lanka 72-3 (20 overs)

Batsmen: Sangakkara 16*, Jayawardene 2*

Fall of wickets: 3-1 (K Perera 3), 4-2 (Dilshan 0), 69-3 (Thirimanne 41)

Bowling figures: Steyn 5-2-13-1, Abbott 5-1-16-1, Morkel 4-1-14-0, Duminy 4-0-15-0, Tahir 3-0-12-1.

Sri Lanka won toss

Scorecard

If this was a T20 then this would have been a woeful effort from Sri Lanka. Sangakkara only has 15 off 51 balls and Jayawardene, the latest man in, scores one off his first five.