Here's the election procedure for Saturday's 2010 vote as outlined on the Fifa website.
The Fifa chief has a casting vote
The 2010 World Cup host will be decided by all the 24 members of Fifa's executive committe in Zurich on 15 May.
The Fifa executive committee will decide which candidates fulfil all Fifa's conditions to participate in the final election, based on the analysis of their bid documents, the Inspection Group's report and the bidders' presentations.
The election will be by secret ballot. Secrecy means the opportunity to fill in the ballot papers without scrutiny from a third party.
The ballot papers shall be viewed after each round only by the General Secretary, a public notary plus an additional third person (KPMG).
If a final decision of the host of the 2010 Fifa World Cup has been taken, the result shall be put into an envelope and brought by the public notary to the press conference, where it will be handed over to the Fifa President for announcement.
Abstentions, empty ballot papers or ballot papers on which more than one candidate is
marked, or ballot papers on which a candidate which has been eliminated in a previous round has been marked, are invalid.
The same applies to ballot papers on which the mark is not clear or illegible. The General Secretary and the public notary will decide on the validity of a ballot paper.
If there are more than two candidates, the absolute majority of the valid ballot papers of the executive committee members present will be required for election (i.e. more than 12 of the ballot papers, provided that all the members are present, no invalid ballot papers and no abstentions).
First round of election: If the first round is not conclusive, the candidate which obtains the fewest number of ballots will be excluded from the second round. Any candidate that does not receive any ballots, is eliminated from the next round.
Intermediate round: If two or more candidates receive equal numbers of fewest ballots, an intermediate round with these candidates will take place to identify the candidate which shall not progress to the next round.
If two or more candidates receive equal numbers of fewest ballots at the intermediate round, the Fifa President will then have the casting vote to decide
which candidate does not progress to the next round.
The decision makers:
President: Sepp Blatter (Switzerland)
Senior Vice President: Julio Grondona (Argentina)
David Will (Scotland)
Lennart Johansson (Sweden)
Issa Hayatou (Cameroon)
Mong Joon Chung (South Korea)
Jack Warner (Trinidad & Tobago)
Angel Maria Villar Llonna (Spain)
Slim Aloulou (Tunisia)
Michel D Hooghe (Belgium)
David Sasso Sasso (Costa Rica)
Ricardo Teixeira (Brazil)
Mohamed Bin Hamman (Qatar)
Senes Erzik (Turkey)
Chuck Blazer (USA)
Worawi Makuda (Thailand)
Nicolas Leoz (Paraguay)
Ismail Bhamjee (Botswana)
Amadou Diakite (Mali)
Viacheslav Koloskov (Russia)
Gerhard Mayer-Vorfelder (Germany)
Michel Platini (France)
Ahongalu Fusimalohi (Tonga)
Junji Ogura (Japan)
Tautulu Roebeck (Samoa)