Born in Amadora, Dias started his career at local club Estrela da Amadora, before moving to Benfica's youth academy in 2008, where he played for the junior side until 2015. In the same year, on 30 September, he made his professional debut with Benfica B in a 2015–16 LigaPro match against Chaves. On 7 March2016, Rui Vitória called eighteen-year-old Dias for Benfica's Champions LeagueRound of 16 second leg tie against Zenit after three of his four main centre-backs were unable to make the trip to Russia. The following season he helped the B team finish fourth; the club's highest ever position obtained in the second division. He also helped the junior team reach the final of the 2016–17 UEFA Youth League. On 16 September 2017, Dias debuted for the first team in a Primeira Liga match against Boavista. After two months of impressive displays, including two games against Manchester United in the Champions League, he underwent surgery due to appendicitis, sidelining him for a month. He scored his first goal for Benfica in a Taça da Liga encounter against Vitória de Setúbal on 29 December 2017. On 3 February 2018, he scored his first goal in the Primeira Liga against Rio Ave. At the end of the season, he was voted Primeira Liga's best young player of the year. After heavy speculation linking Dias to a big money move to French side Lyon, he extended his contract with Benfica until 2023.
International career
Dias represented the Under-17 side at the 2014 Under-17 Euro. Two years later, he captained the Under-19 squad at the 2016 Under-19 Euro. The following year he captained the Under-20 side at the 2017 U-20 World Cup. On 5 September 2017, he made his debut for the Under-21s in a 2019 Euro qualifying match against Wales. Dias was called up to the senior side by Portugal manager Fernando Santos on 15 March 2018, ahead of international friendlies against Egypt and the Netherlands. However, four days later he was dropped from the squad after picking up right ankle sprain. On 17 May 2018, Dias was named in Portugal's 23-man squad for the FIFA World Cup in Russia. Eleven days later, he made his international debut in a friendly against Tunisia. Despite being present at the World Cup, he did not feature in any of Portugal's four matches in the competition.
