Three months ahead of the vote to decide the winning bid, an evaluation commission report drafted after visits to the cities earlier this year and released on Tuesday had all three hopefuls locked in a dead-heat.
According to the report the struggling Spanish economy was of no risk to Madrid, security in Turkey did not threaten Istanbul's chances and Tokyo's low public support was offset by praise for a solid bid and financial strength.
The winning city will be selected at the 125th IOC Session in Buenos Aires, Argentina in September.
The report's release comes just days before a key meeting in Lausanne on July 3-4 when the bid cities will present their plans to the entire membership of the IOC.
"In presenting this technical report, the 2020 Evaluation Commission wishes to record that the projects of the three candidate cities are of a high quality and that each city offers a unique approach to organising the Games," the IOC said.
Istanbul, bidding for the fifth time in the last six votes, received a thumbs-up for government backing, wide public support and the capability of delivering construction for the Games on time.
"The Commission is confident that given the government's full support and the proven track-record of (state construction company) TOKI to date... construction works could be funded and completed on time."
Travel times to venues, however, were seen as somewhat optimistic given the large city's traffic issues.
The report was drafted before the start of nationwide protests against the government of Prime Minister Tayyip Erdogan. The unrest began at the end of May when police used force against campaigners opposed to plans to redevelop a central Istanbul park.
The report noted the country could successfully safeguard the event despite security problems with neighbouring Syria and the Kurdistan Workers Party (PKK) guerrillas.
The issue of the Turkey protests are expected to be a talking point at the Lausanne meeting.
Tokyo, which failed to land the 2016 Olympics, has already created a $4.5 billion reserve fund for the Games, a major asset in its bid, the IOC said.
"Despite a significant construction programme, the Commission is confident that work could be completed on time and that Tokyo has the necessary financial strength to do so through the TMG's "Hosting Reserve Fund" of $4.5 billion, earmarked for venue construction," it said.
The IOC also said the new venues would create a "long-term foundation" for those sports in the country.
"The Commission is confident that the Japanese economy would be able to support the necessary infrastructure development needed for the delivery of the Games."
The Japanese capital, however, is lagging behind both its rivals in public support.
Madrid won high marks for its compact bid in its third straight attempt to land the Games, with no major investment in transport needed due to the city's existing infrastructure.
Spain's current economic recession also represented no major risk to the Games should the city be picked, the IOC said.
"The Commission believes that the degree of financial risk facing Madrid 2020 should be manageable over seven years within the overall Spanish economy and taking into account government guarantees. All required financial guarantees were provided.," it said.
- Politics & Government