The 2009 Duel in the Pool was a swimming competition between a team from the United States and a combined British, German and Italian "E-Stars" team held on Friday 18 and Saturday 19 December 2009 at the Manchester Aquatics Centre, United Kingdom. The naming rights are held by Mutual of Omaha and British Gas in the United States and Europe respectively – the event was therefore promoted as the 2009 Mutual of Omaha Duel in the Pool and 2009 British Gas Duel in the Pool.

Rebecca Adlington is an English former competitive swimmer who specialised in freestyle events in international competition. She won two gold medals at the 2008 Summer Olympics in the 400-metre freestyle and 800-metre freestyle, breaking the 19-year-old world record of Janet Evans in the 800-metre final. Adlington was Britain's first Olympic swimming champion since 1988, and the first British swimmer to win two Olympic gold medals since 1908. After winning her first World Championship gold over 800 metres in 2011, along with silver in the 400 metres at the same meet, she won bronze medals in both the women's 400-metre and 800-metre freestyle events in the 2012 Summer Olympics in London. Adlington is one of the few people to have won Olympic Games, World Championships, continental championships and Commonwealth Games gold medals, although she did not win a set in any one event.