Los Angeles and Paris are expecting a final decision on their bids to host the 2024 Olympic Games.
The American and French committees have gathered at the Swiss Tech Convention Centre in Lausanne, to present their cases.
Hamburg, Rome and Budapest were originally in contention, but have since withdrawn to leave just the French and Californian cities.
French President Emmanuel Macron said the Paris bid was the strongest defender of Olympic values of openness, tolerance and respect for the environment, principles he said were being challenged by others.
Paris is widely regarded as favourite for the 2024 Games, with Los Angeles set to be awarded them four years later.
The International Olympic Committee’s decision is likely to be approved in Lausanne in the coming days.