Rarely, if ever, has so much been on the line at a single Olympic meeting. When International Olympic Committee members gather next week in Buenos Aires, Argentina, they will be faced with three decisions that will shape the direction of the Olympic movement for the next decade.

At stake: Choosing the host city of the 2020 Olympics, electing a new IOC president to succeed Jacques Rogge and selecting one sport to add to the 2020 programme.

The favourites: Tokyo, Thomas Bach and wrestling.

Election extravaganza

Prime ministers, royalty, sports stars and celebrities will be part of the election extravaganza at the IOC session. The week long meetings will have the flavour of a political carnival replete with last-minute campaigning, backstage vote-chasing and round-the-clock lobbying by spin doctors, consultants and strategists.

While most IOC members are primarily interested in the September 10 presidential election, the first big vote comes on September 7 with a secret ballot on the 2020 host city.

It's a three-way contest between Tokyo, Madrid and Istanbul.

All three are repeat candidates: Istanbul is making its fifth overall bid, Madrid a third straight attempt and Tokyo a second try in a row.

Tokyo has been seen as a slight front-runner, though the leak of radioactive water from the Fukushima nuclear plant is causing concern. Madrid, once counted out because of Spain's economic crisis, has picked up momentum recently and now looks like a legitimate challenger. Istanbul has slipped following the anti-government protests and doping scandals in Turkey and the escalating war in neighbouring Syria.