National team coaches and captains as well as journalists from around the world have voted for the winner, with an initial 23-man shortlist being reduced to three last month.
Messi is a contender to win the trophy for a fifth successive year, but few are talking about the Barcelona star this time, with Bayern Munich's Ribery hoping his remarkable season at club level gives him the edge against the goalscoring exploits of Real Madrid and Portugal's Ronaldo.
Prior to that, Ribery had been the favourite, but the extension came immediately after Ronaldo's hat-trick helped Portugal beat Sweden in a play-off to qualify for the World Cup.
That played into the hands of the 28-year-old, who is hoping to win the award for the second time following his success in 2008.
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Ronaldo himself claims he is not obsessed with the award, although he admits that he has saved a space for it in his recently-opened museum on his native island of Madeira.
Ronaldo won nothing with Real Madrid or with Portugal in 2013, but the Ballon d'Or is an individual award and there can be little doubting the individual quality of a player who scored 66 goals in 56 games for club and country in the calendar year.