Cardiff: South Africa will become the first team to top the International Cricket Council's rankings in all three formats of the game if they beat England in the first one-dayer in Cardiff on Friday.
Having surrendered the number one Test ranking to the Proteas upon losing the series on Monday, England must now defend top spot in the 50-over game.
Alastair Cook's side have won their last 10 one-day internationals. The Proteas will top the table if they win the five-game series 3-2 or better.
However, either side could drop as low as third in the ODI rankings depending on the results of Australia's three-game series against Pakistan in the United Arab Emirates, which begins next Tuesday after a one-off ODI between Afghanistan and Australia in Sharjah on Saturday.
One-day captain Cook hopes England can put the Test series behind them - as well as the row over batsman Kevin Pietersen, who was dropped from the Test side after sending "provocative" text messages to South African players that were alleged to be insulting towards Test skipper Andrew Strauss.
Pietersen was not named in the squad for this one-day series or the upcoming ICC World Twenty20, despite making himself available.
Pietersen's decision in May to retire from limited-overs internationals preceded two wins over West Indies before the third ODI was washed out by rain, while the five-game series with Australia produced four England wins and one abandonment.
Cook will be presented with the ICC's ODI shield before the game.
Teams from:
England: Alastair Cook (captain), Ian Bell, Jonathan Trott, Ravi Bopara, Eoin Morgan, Craig Kieswetter (wk), Tim Bresnan, Graeme Swann, Steven Finn, Jonathan Bairstow, James Anderson, Jade Dernbach, Samit Patel, Chris Woakes
South Africa: Hashim Amla, Graeme Smith, Jean-Paul Duminy, AB de Villiers (captain & wk), Imran Tahir, Faf du Plessis, Albie Morkel, Robin Peterson, Dale Steyn, Morne Morkel, Lonwabo Tsotsobe, Dean Elgar, Ryan McLaren, Wayne Parnell, Justin Ontong
Pitch and conditions
Pitches in Cardiff tend to be on the slow side and can help the spinners. The weather forecast is not great, with the chance of some rain during the day.
Stats and trivia
Match facts
Friday August 24, 2012
Start time 10.15am local (0915 GMT)