The Champions League will return in August with the quarter-finals onwards being played as one-off games in Lisbon, European football's governing body UEFA said on Wednesday.
The Europa League will be completed in western Germany in the same month and is currently expected to be without fans after both tournaments were suspended in March because of the coronavirus pandemic.
The remaining last 16 games will be played early in August with a decision pending on most venues.
Porto and Guimaraes will be added to Benfica and Sporting's stadiums in Lisbon for the Champions League last 16 on August 7 and 8 if the respective home teams cannot host their ties. The final will be at Benfica's Estadio da Luz on August 23.
The Europa League final will be in Cologne on August 21 with other games in Duisburg, Dusseldorf and Gelsenkirchen. The women's Champions League will conclude in a similar way in Bilbao and San Sebastian (Spain) in August.
UEFA president Aleksander Ceferin told a virtual news conference that at the moment the games would be behind closed doors but that he would stay in contact with national governments.
Next season's competition
UEFA said it would not be possible to register newly transferred players for the resumption of its competitions, meaning RB Leipzig's Chelsea-bound striker Timo Werner looks set not to be able to play for the Londoners. Three new players may be added to squads but they must be existing players on a club's books.
Istanbul and Gdansk were meant to hold the finals of the two men's competitions but they will now host the showpiece events at the end of next season.
Next season's men's European club competition group stages will begin with their usual format in October. The qualifying rounds of the two competitions will be played in single legs in August and September, with the only exception being September's Champions League play-offs which will remain over two legs.
The draw will determine which club will play the single leg at home.
The European Championships, already pushed back from this June and July to next year, will remain with 12 host cities across the continent with a fixture list now set from June 11-July 11.
The Euro 2020 play-offs will take place in October and November as triple headers with the Nations League starting in September.