England gave a debut to 25-year-old Warwickshire off-spinner Alex Loudon. He replaced Yorkshire seamer Tim Bresnan in the only change to the team that lost Tuesday's second One-day international at The Oval by 46 runs.
Sri Lanka made two changes. Malinga Bandara, a leg-spinner, replaced star bowler Muttiah Muralitharan after the off-spinner flew out of England on Friday to be with his ill son.
Meanwhile Dilhara Fernando, who took three for 51 in Sri Lanka's 20-run series-opening win at Lord's but missed the Oval match with an ankle injury, returned in place of fellow paceman Ruchira Perera.
Sri Lanka, 2-0 up in the five-match encounter, knew victory here would see them clinch the series ahead of next week's matches at Old Trafford and Headingley.
England: Marcus Trescothick, Andrew Strauss (capt), Ian Bell, Kevin Pietersen, Paul Collingwood, James Dalrymple, Geraint Jones (wkt), Alex Loudon, Liam Plunkett, Sajid Mahmood, Stephen Harmison
Sri Lanka: Upul Tharanga, Sanath Jayasuriya, Mahela Jayawardene (capt), Tillakaratne Dilshan, Kumar Sangakkara (wkt), Russel Arnold, Farveez Maharoof, Dilhara Fernadndo, Chaminda Vaas, Lasith Malinga, Malinga Bandara