The International Paralympic Committee (IPC) has suspended its zero classification policy and will allow athletes in ten sports to be graded in the host city before Tokyo 2020.
Introduced in 2014, the policy bans classification taking place at the Paralympic Games in order to prevent disruption that would be caused by a last minute decision.
However, with some sports facing coronavirus challenges as they try to classify all of their athletes before Tokyo 2020, the IPC has opted to put the rule on hold.
It follows "extensive consultation" with International Federations and the Tokyo 2020 Organising Committee, and a desire to ensure that no athlete misses out on competing in Japan this year due to classification opportunities not being available.
The ten sports which will be able to classify in Tokyo are athletics, boccia, canoeing, cycling, judo, rowing, sitting volleyball, swimming, wheelchair rugby and wheelchair tennis.
These all have a larger pool of potential athletes requiring classification or a limited ability to schedule classifying events due to COVID-19.
Each sport has identified its maximum number of prospective Tokyo 2020 athletes and National Paralympic Committees (NPCs) are still being asked to classify as many as possible before the Games.
The IPC said it hopes to confirm the number of athletes who will be classified in Tokyo immediately prior to the event.
"Ensuring that athletes are classified prior to competing at the Tokyo 2020 Paralympic Games is crucial to safeguarding the integrity and credibility of the competition," said IPC President Andrew Parsons.
" I would like to thank Tokyo 2020 for their flexibility in working with us to find a solution to the issue we face.
"Since the pandemic began, our classification department has worked tirelessly with the International Federations to provide safe and secure classification.
"The reality is that for many sports classification and competition opportunities remain limited, while for others the disruption caused by the pandemic has had a significant impact on athletes' ability to attend classification before the Games.
"This decision to provide classification opportunities at the Tokyo 2020 Paralympic Games has not been taken lightly by the IPC, bearing in mind the potential impact on athletes who may change class or be found non-eligible at such a late stage.
"However, the pros outweigh the cons in this matter, and we believe this decision will be welcomed by the athlete community, NPCs and International Federations, relieving some of the pressure they face.
"With less than 150 days to go until the Games, I strongly encourage NPCs to ensure they do everything they can to still get their athletes classified ahead of the Games as the number of athletes who will be able to be classified in Tokyo will be limited."
The Tokyo 2020 Paralympics are now due to run between August 24 and September 5 after being pushed back a year due to the global health crisis.
Athletes must have a "confirmed" sports status or a "fixed review date" later than December 31 in order to be eligible.
Classification determines who is eligible for Para-sport and ensures athletes compete against others who are similarly impaired.
The IPC said the zero classification policy would return for the Beijing 2022 Winter Paralympics.