Right-back - Joao Cancelo (Manchester City)
Joao Cancelo was one of Manchester City's key players this season, helping them romp to the Premier League title and reach the Champions League final.
Cancelo did not enjoy a good first season with Manchester City but was highly impressive during his second season. Utilised in both full-back positions by Manchester City boss Pep Guardiola, the 27-year old shone, thanks to his technical prowess.
Comfortable in possession, the former Inter Milan and Juventus player made 28 Premier League appearances, scoring two goals and providing three assists. He could be an asset at Euro 2020.
Cancelo has played 26 games for Portugal, scoring four goals and providing three assists.
Centre-back - Pepe (Porto)
Pepe is still going strong at the age of 38. He enjoyed another excellent season with Portuguese giants Porto and could be a vital player for Portugal at Euro 2020.
The centre-back, renowned for his spell with Real Madrid, where he made 334 appearances in all competitions, is currently in his second stint with Porto. An aggressive centre-back, Pepe has often been criticised for his style of play, but it is hard to argue about his quality as a defender.
Pepe has had 113 caps for Portugal, and his experience will be vital for the Portugal backline at Euro 2020. He will have to curb his enthusiasm on occasions, though.
Centre-back- Ruben Dias (Manchester City)
Arguably the best centre-back in the world right now, Ruben Dias enjoyed a stellar debut season with Manchester City and is almost a certainty to start at Euro 2020.
Eyebrows were raised when Manchester City splurged £61.2 million last summer to acquire him from Benfica. However, Dias responded in fine fashion. The 24-year old is a physically gifted, aggressive centre-back who is comfortable on the ball.
Such were Dias' performances for Manchester City this season that he has been nominated for the PFA Player of the Year award.
If Manchester City had won the Champions League, it would not have been surprising to see the centre-back receive a Ballon d'Or nomination as well. A strong Euro 2020 campaign for Portugal could still see Dias secure that nomination.
Left-back- Raphael Guerreiro (Borussia Dortmund)
One of the most underrated players in the game, Raphael Guerreiro, has had a wonderful spell at Borussia Dortmund.
Guerreiro joined Borussia Dortmund from Lorient in 2016 for £10.8 million. He has been a consistent presence in the Dortmund first XI in four of his five seasons at the club. Capable of playing as a left-back and in midfield, the 27-year old will be an useful player to have at Euro 2020.
The former Caen man made 27 Bundesliga appearances this season for Borussia Dortmund, scoring five goals and providing ten assists. At Euro 2020, his passing and creativity could be key for Portugal.
Guerreiro has made 45 appearances for Portugal, including five in their victorious Euro 2016 campaign.
Other options: Nelson Semedo (Wolverhampton Wanderers), Jose Fonte (Lille), Nuno Mendes (Sporting CP)