Olympic chiefs will meet in Lausanne on Tuesday to discuss and likely rubberstamp the process to award the 2024 and 2028 Games simultaneously.
Members of the International Olympic Committee (IOC) will hold an extraordinary session after presentations by the campaign teams for Los Angeles and Paris, battling for the right to succeed 2020 hosts Tokyo and stage the Games in seven years' time.
In June, IOC bosses backed a plan to award both the 2024 and 2028 Games together, with the recommendation expected to be backed by a vote at their Swiss headquarters on Tuesday.
IOC president Thomas Bach opened a ground-breaking week for the Olympic movement on Sunday by telling IOC top brass: "We'll have some interesting days in Lausanne. Some very important decisions will be taken. More decisions will be made in Lima."
The Peruvian capital Lima hosts the 130th IOC Congress on September 13 where the vote to decide the 2024 and likely 2028 hosts will be made.
Both Paris, whose delegation is being led by French President Emmanuel Macron, and Los Angeles will present their bids to the IOC on Tuesday.
Last week the IOC Evaluation Commission report lavished praise on both bidding cities, stating there was "very little to separate" the two rivals.
"Members of the Evaluation Commission have used the terms 'forward-looking', 'innovative', 'vibrant' and 'cool' to describe the Los Angeles candidature, and 'historical', 'cultural', 'iconic' and 'amazing backdrops' for that of Paris," said Patrick Baumann, IOC member and chair of the 2024 Evaluation Commission.
"However, whatever the description, it truly is a tale of two great Olympic cities. The two projects are different in nature, but each city presents a proposal which is genuinely authentic and reflects the best of what each has to offer."
The IOC report noted that in line with the reforms of Olympic Agenda 2020, both Los Angeles and Paris are planning to use a record number of existing and temporary venues, a first in Olympic history and a move designed to cut costs and boost sustainability.
Bach said the proposal to award the two Games had been "unanimously" endorsed, adding the IOC had a "golden opportunity" with two "great cities" competing for 2024 and did not want to turn either away, particularly at a time when interest in hosting Olympics has faded, with cities increasingly reluctant to take on the vast expense.
But a double awarding would not be a first, the IOC having, in 1921, awarded the 1924 and 1928 Summer Games to Paris and Amsterdam, as well as later promising Los Angeles the 1932 Games.
Pierre de Coubertin, the founder of the modern Olympics, had pushed for the joint awarding as the world, and Europe in particular, struggled to rebound after the devastating First World War.