Lisbon is the favorite to host an August eight-team Champions League knockout tournament if the governing body Uefa gives it the go-ahead.
Uefa plans to shift the final for the new format from Istanbul, where it was expected to take place on 30 May.
The Europa League final is likely to be moved to Germany, due to take place in Gdansk, Poland on May 27.
Due to the coronavirus pandemic, continental cup competitions in Europe were halted in March.
On 17 June the executive committee of Uefa will take its decision.
Meetings have debated various scenarios over the past few weeks, including completing the tournament in two-legged ties as originally planned.
But recent discussions have centered on the type of world governing body structure that Fifa is looking for with its idea of the Club World Cup, which it is felt will provide broadcasters and TV audiences with the most exciting choice.
It would mean that the quarter-finals, semi-finals, and final are played as a mini-tournament behind closed doors at one location.
The final of the Champions League would be played on August 23, with the finale of the Europa League on August 21.
Spain, Germany, and Russia were mentioned as potential hosts for the Champions League but given its location and the fact that there are no teams left in the tournament this season, Portugal is seen as the most likely option.
Lisbon has two stadiums that have the facilities to host high-profile matches, and hotels to accommodate the number of teams necessary.
The Portuguese Primeira Liga resumed on 3 June and this month most of the country’s coronavirus restrictions are lifted.
The Bundesliga resumed in Germany on 16 May, and stadiums in Gelsenkirchen, Cologne, Duisberg, and Dusseldorf are likely to stage games for the Europa League.