London: South Africa have won the toss and will bat, which could be crucial in determining whether they will end this match ranked as Test No. 1.
Lord's is usually a good place to bat, though the effects of the Olympic archery do throw a little uncertainty into the mix.
An unchanged South African side lead the 3 match series 1-0 and will become the World number 1 side in Test cricket if they end with a series victory.
England meanwhile, have brought back Swann to supplement a three-man pace attack of Finn, on his home ground, James Anderson and Stuart Broad.
Teams:
England: Andrew Strauss (capt), Alastair Cook, Jonathan Trott, Ian Bell, Jonathan Bairstow, James Taylor, Matt Prior (wk), Stuart Broad, Graeme Swann, Steven Finn, James Anderson
South Africa: Graeme Smith (captain), Alviro Petersen, Hashim Amla, Jacques Kallis, AB de Villiers (wk), Jacques Rudolph, Jean-Paul Duminy, Imran Tahir, Morne Morkel, Vernon Philander, Dale Steyn