English fans attending the Champions League final in Porto between Manchester City and Chelsea will have to fly in and out of the country on the day of the match, the Portuguese government said.
They will also need to stay in a 'bubble' while in the city.
Uefa announced on Thursday that 6,000 fans from each club will be able to attend the final on 29 May.
The final was moved from Turkey because of coronavirus restrictions.
Portugal is on England's green list so players and fans can attend without having to quarantine on their return home. Turkey is on the red list.
Portugal's cabinet affairs minister Mariana Vieira da Silva said a set of rules had been put in place for those fans attending the final.
"Those who come to the final of the Champions League will come and return on the same day, with a test done, in a bubble situation, on charter flights," she said.
"There will be two fan zones and from there they will be moved to the stadium and from the stadium to the airport, being in Portugal less than 24 hours.
"Obviously those coming by plane [to be in Porto while the match is on but do not actually go the stadium] will comply with the established rules and security measures will be put in place as happened in Lisbon last year."
She said the restrictions put in place were to ensure that Covid rates remain low in Portugal.
Vieira da Silva said that the local health authority was in charge of selecting seats for fans to ensure social distancing and that tickets were non-transferable.
Manchester City said on their website that the club would be "offering qualifying supporters an official day trip travel package from Manchester to Porto".
The final had been due to be staged at Istanbul's Ataturk Olympic Stadium.
"To deprive supporters of the chance to see the match in person was not an option and I am delighted that this compromise has been found," said Uefa president Aleksander Ceferin.
Uefa, UK government officials and the Football Association met to talk about Wembley hosting the game but no agreement could be reached on quarantine exemptions for sponsors, VIPs and broadcasters.
"Fans have had to suffer more than 12 months without the ability to see their teams live and reaching a Champions League final is the pinnacle of club football," added Ceferin.
"After the year that fans have endured, it is not right that they don't have the chance to watch their teams in the biggest game of the season."
Both Chelsea and Manchester City say they are in discussions with Uefa and other stakeholders over ticketing and travel arrangements.
City say they will offer fans a day-trip travel package from Manchester to Porto for the 20:00 BST match.
The sale of tickets to the general public will start on 24 May 2021 at 13:00 BST.
It is the second successive year the final has been held in Portugal with Lisbon the location for the delayed final stages of last season's competition, won by Bayern Munich.
The final capacity limit at the Estadio do Dragao in Porto is still to be fixed.
Ceferin acknowledged that the UK government's decision to place Turkey on the red list for travel was made in good faith but said it also left the governing body with "a major challenge".
"The difficulties of moving the final are great and the FA and the authorities made every effort to try to stage the match in England, and I would like to thank them for their work in trying to make it happen," he added.
"The Turkish Football Federation and the authorities have always been reliable partners of Uefa and I hope to be in Istanbul and Turkey for a Champions League final and many other events in the near future.
"I hope the final will be a symbol of hope at the re-emergence of Europe from a difficult period and that the fans who travel to the game will once again be able to lend their voices to showcase this final as the best in club football."