A win for South Africa will give them an unassailable 2-0 lead, while England need to find ways to stop Hashim Amla.
London: England will have to quickly come out of the shock news of Andrew Strauss' retirement and put one across South Africa in the third ODI at The Oval to prevent the visitors from taking an unassailable 2-0 lead in the series that has been reduced to a four-match affair after the washout at Cardiff.
South Africa created history at The Rose Bowl earlier in the week when they became the first team to sit on top of the ICC rankings in all forms of cricket - Tests, ODIs and T20s. By winning that match by 80 runs, the South Africans replaced England as the No. 1 ODI team after ending their stint on top of the Test rankings earlier on the tour.
Graeme Smith's men have inflicted one would after another on England this summer. The chain of unsettling events - starting from losing the No. 1 Test rank to Strauss' retirement - has now reached a stage where the hosts stare at losing the ODI series as well.
England bowlers - who have been pivotal to the team's success at home - have so far had no answers to the South African batting, especially Hashim Amla who continues to spread his terror in a nonchalant manner.
Amla has so far had just one innings in the ODI series, where he sent England into submission mode with his match-winning 124-ball 150 after topping the run-scoring charts in the Test series with 482 runs, including two hundreds - one of which was a triple century (311*). He will come out to bat at The Oval with the added confidence of having been named in the ICC Test XI for the third consecutive year and being nominated for the 'ICC Cricket of the Year' and 'ICC Test Cricketer of the Year' awards.
South Africa captain Graeme Smith - who scored 52 in an 89-run opening partnership with Amla at Southampton - will not be too worried about changing his XI in London despite failure of the middle order to press on after being 165 for 2 in the first ODI.
JP Duminy, Dean Elgar and AB de Villiers failed to make any notable contributions, leaving it to Amla to take South Africa close to 300. Perhaps Smith has a case to push de Villiers up the order to not let the momentum drop and then have Duminy lower down to take care should there be a stutter on the way.
If any, Dale Steyn could be the only change in the visitors' line-up, that's if Smith doesn't want to keep him in the safe for the next month's World Twenty20. Steyn wasn't in the XI for the first two ODIs either and the best excuse on offer is that Smith is preserving his best bowler for the T20 battlefield in Sri Lanka.
Morne Morkel, Lonwabo Tsotsobe, Wayne Parnell, Ryna McLaren and Robin Peterson restricted England to 207 in the first ODI. That should give Smith enough confidence to go in with the same bowling line-up.
England's problems largely revolve around Amla, who hasn't looked like getting out to any of the English bowlers - slow or fast. If Tim Bresnan leaked 7.62 runs per over at Southampton, Steven Finn (10-0-59-1) and James Anderson (9-0-53-0) were just shy of six runs per over. Their two spinners Graeme Swann and Samit Patel could bargain only two wickets for 97 runs in 20 overs - with Swann being the wicket-taker on both the occasions.
But Swann has been rested for the last three ODIS, which could add to England's woes. Offspinner James Tredwell has taken Swann's place and is expected to replace him straight into the XI. However, it will be interesting if Cook takes a call on James Anderson as well, with the bowler looking jaded after the Test series. If Anderson is rested, Jade Dernbach is likely to take his place, but with a must-win match on hands, Cook will need Anderson's experience for crunch situations.
When it comes to batting, the hosts' problems again revolve around one man, albeit it's his absence than presence that's causing problems - Kevin Pietersen.
Bell has been pushed up and looked good in the 45 he scored the other day, but captain Cook and No. 3 Jonathan Trott need to complement Bell for a healthy start and give confidence to a strong-looking but under-performing middle order of Ravi Bopara, Eoin Morgan and Craig Kieswetter.
But it's not just about batting well for England, it’s about batting well against an in-form bowling attack. That's where the battle lies for the hosts if they want to live another day in this ODI series.
England: 1 Alastair Cook (capt), 2 Ian Bell, 3 Jonathan Trott, 4 Ravi Bopara, 5 Eoin Morgan, 6 Craig Kieswetter (wk), 7 Tim Bresnan, 8 Samit Patel, 9 James Tredwell, 10 James Anderson/Jade Dernbach, 11 Steven Finn
South Africa: 1 Hashim Amla, 2 Graeme Smith, 3 AB de Villiers (capt/wk), 4 Dean Elgar, 5 JP Duminy, 6 Faf du Plessis, 7 Wayne Parnell, 8 Ryan McLaren, 9 Robin Peterson, 10 Morne Morkel, 11 Lonwabo Tsotsobe