Australia and South Africa in Cricket World Cup action on Saturday

David Warner has had a big impact for Australia at the World Cup, with two fifties and a hundred in four games

For Australia it is should-win while for South Africa it is must-win in Saturday's Cricket World Cup double header.

Australia, who have won three of their four games so far, will be expected to dispatch of a Sri Lanka side who were thumped by New Zealand in their opener, scraped past Afghanistan in their second game and then had their matches with Bangladesh and Pakistan wiped out by rain.

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Highlights as David Warner's first hundred for Australia since the ball-tampering scandal helped his side see off Pakistan.

David Warner scored his first century for Australia since his ball-tampering ban elapsed in Wednesday's thrilling victory over Pakistan and also passed fifty in their triumph over Afghanistan as well as their 36-run loss to India.

The 32-year-old has enjoyed his World Cup so far but South Africa have not enjoyed theirs - three straight defeats to kick off the competition, against hosts and favourites England and then Bangladesh and India, and then a washout against West Indies in Southampton on Monday.

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Australia captain Aaron Finch says having David Warner and Steve Smith back in the ring 'adds a huge amount of presence'.

The point the Proteas picked up from Monday's rain-wrecked match just about keeps them in the hunt for a top-four place but they probably need to win their final five fixtures to have any chance of progressing, which would mean knocking off high-flying Australia and New Zealand.

Afghanistan are also winless, with defeats to Australia and Sri Lanka followed by another against New Zealand, but may well fancy their chances against a beleaguered South Africa.

TEAM NEWS

Australia quicks Mitchell Starc and Pat Cummins were potent against Pakistan but the rest of the attack not so. Spinners Adam Zampa and Nathan Lyon and left-arm seamer Jason Behrendorff may, therefore, hope to play, but the expectation is that Aaron Finch will select an unchanged XI.

Pat Cummins has taken nine wickets at an average of 18.77 through Australia's first four games

Marcus Stoinis will again sit out as he continues to recover from a side strain. The Australian selectors are giving him every chance to prove his fitness ahead of their next match against Bangladesh, on Thursday, before deciding on his future in the tournament. Mitchell Marsh has been flown in as cover, but can't be called into the squad until such a time as Stoinis is officially ruled out.

Lasith Malinga is four wickets away from 50 in World Cups - he'd be only the fourth bowler to ever reach the mark

Lasith Malinga is back with the Sri Lanka side after attending his mother-in-law's funeral. He should likely play, with a four-wicket haul taking him to 50 World Cup scalps.

Down in Cardiff, South Africa will make a late call on whether paceman Lungi Ngidi is fit to return. Ngidi pulled up with a tight hamstring in the defeat to Bangladesh earlier in the tournament and has subsequently missed their last two games. If he does play, left-armer Beuran Hendricks is the most likely to make way, despite not bowling a ball in the West Indies washout.

Fast bowler Lungi Ngidi hopes to return for South Africa after missing their last two defeats

As for Afghanistan, offspinner Mujeeb ur Rahman is unlikely to be recalled due to the seamer-friendly conditions likely in south Wales, though Dawlat Zadran could come back in if he is fit. Rashid Khan should play, having recovered from the blow to the head he suffered during the defeat to New Zealand.

PLAYERS TO WATCH

No one has taken more ODI wickets in 2019 than Cummins, who has bagged 26 in 10 games, including three against Pakistan last time out. It could be a fascinating battle if Sri Lanka openers Dimuth Karunaratne and Kusal Perera hit their straps, they have hit one fifty apiece so far.

Quinton de Kock struck a half century against England in South Africa's opening game but has struggled since

For South Africa, given his undoubted talent, it's about time Quinton de Kock fired for them at the top of the order as they look to dig themselves out of this World Cup hole. A strong showing of 68 in the tournament opener against England has been followed up with scores of just 23, 10 and 17no. For Afghanistan, it's the familiar name of legspin maestro Rashid, though he has been fairly quiet so far, with just three wickets over three games.

WHAT ARE THEY SAYING?

Sri Lanka captain Dimuth Karunaratne hopes his 'underdogs' can cause an upset against Australia

Sri Lanka captain Dimuth Karunaratne on his side being underdogs: "We are a team with limited talent. If you compare us with a lot of other sides, we have major limitations. For example, the India side has someone who hits a hundred virtually in every match. In our team, we've only had one or two centurions all year."

Australia coach Justin Langer on Pat Cummins: "I think he's always been a competitive beast. He loves the challenge, he loves the contest. I've never seen anything different since he was in the Under-19s, [as] an 18-year-old he used to love it. That's what the greats do, that's what the champions do. They love the contest. He loves the contest."

Faf du Plessis is confident South Africa have the talent to be able to turn their disastrous World Cup form around

South Africa captain Faf du Plessis on how his team can still qualify: "I truly believe that if we carry those ghosts of the last week with us it's going to be tough to get out of the hole. We've got to win the five games and that clarity is what we're trying to achieve. Hopefully that allows the guys to play the way that we can and, if we do that, we'll be a very dangerous team."

Afghanistan captain Gulbadin Naib is still daring to dream: "Obviously we have lost three games, but we have still a chance. Everyone has nine games, so nobody can say who will be in the top four. "

Watch Sri Lanka vs Australia, live on Sky Sports Cricket World Cup from 10am on Saturday, with South Africa vs Afghanistan available from 1pm.