Rugby returns to the Olympics at Rio 2016 after a 92-year hiatus -- but in the seven-a-side version instead of the 15-man code used in previous versions.
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New Zealand's Sonny Bill Williams, who gave his Rugby World Cup winner's medal to young fan Charlie Lines after October's final at Twickenham, is among a number of union stars hoping to go for sevens gold in Brazil.
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All Blacks center Williams has never played sevens, but wants to join other illustrious sportsmen such as Usain Bolt to have tasted Olympic glory.
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As a former New Zealand heavyweight boxing champion, Williams is also keen to emulate Muhammad Ali, who won light heavyweight gold in the 1960 Olympics in Rome as Cassius Clay.
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Australian fly-half Quade Cooper could also follow his close friend and fellow part-time boxer Williams to Rio after securing a clause in his Toulon contract to play sevens.
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South Africa's record try-scorer Bryan Habana is another of rugby union's big names keen to play at the Olympics. He is one of several Springboks players included in a provisional squad for the 2015-16 World Series.
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The last time rugby was included at the Olympics was in 1924 in Paris. Here the U.S. (in white) takes on Devonport Services in a warmup game in April that year.
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The U.S. beat France in the final to win gold in the Colombes Stadium -- the fourth time rugby had appeared at the Games since its debut in 1900.