Fans of English, German and French clubs will be able to stand for home matches during men's UEFA club competitions in the 2022-23 season.
UEFA on Wednesday launched a programme to observe the use of standing facilities, which were previously only able to be used for domestic fixtures.
The governing body of European football will look at the use of standing in both domestic and international club games, with the aim of assessing if and under what conditions it may be reintroduced in UEFA competitions in a safe manner.
The Standing Facilities Observer Programme 2022-23 will initially be limited to clubs from the top five associations in the UEFA rankings where standing is already authorised and implemented at domestic level.
Fans supporting teams in those countries will be allowed to stand for home Champions League, Europa League and Conference League games at each round of the competitions, other than the finals.
Independent experts will be appointed by UEFA to analyse the use of standing, with the task of assessing the different dynamics between national and international supporters and the related safety and security implications.
At the conclusion of the upcoming campaign, UEFA administration will assess the findings of the programme and submit the results to the UEFA Executive Committee, which will decide on any continuation and possible extension of the programme.