“It is really exciting to be part of such a talented squad and to play for a world-class manager like Pep Guardiola, who has a proven track record of developing young players like myself.
“I believe I can improve here, at a club whose ambitions match my own and I will give everything to be successful and win titles.”
Jorginho Heads To PSG
Guardiola had been seeking a right-sided centre-back since Vincent Kompany left last year.
Dias has impressed during three seasons at Benfica and was in Portugal’s 2018 World Cup squad.
The 23-year-old scored and captained the side in Benfica’s 2-0 win over Moreirense on Saturday, after which he was pictured hugging the club’s sporting director Rui Costa.
City director of football, Txiki Begiristain, added: “Ruben is a player we have admired for some time and we have been impressed with how he has progressed at Benfica.
“He has developed into a real leader and as a defender, he has all the attributes we are looking for. He is strong in the air, good in one v one situations and technically, he is very good, so we are confident he can thrive in our system.
“He is young, but has experience playing for a top European club in Benfica and we’re really pleased we’ve been able to sign him.
“He is another talented addition to the squad and someone who is only going to get better working under Pep.”
Kalidou Koulibaly had been City’s top target but Napoli’s sporting director Cristiano Giuntoli recently told Sky in Italy the defender would be staying with the Serie A side this summer, while Sevilla’s Jules Kounde was also previously linked with a move to the Etihad.
City also denied placing a £78m bid for Atletico Madrid centre-back Jose Gimenez, after the La Liga club’s president claimed he had rejected an offer for the central defender.
Otamendi, 32, won two Premier League titles with City following his arrival from Valencia in 2015.
“They were five wonderful years, not just in a footballing sense, but also at a club where they treat you in the best way possible, from the chefs to the kitmen, through to the backroom staff,” Otamendi told the club’s website.
“I’ve had the opportunity to win two Premier Leagues, to win the Carabao Cup, the FA Cup and the Community Shield. If you win titles it is because you are doing things well, and so I’m happy to have enjoyed these moments, and more than grateful.
“I was lucky enough since the first year I arrived to win a trophy, and later with the arrival of Pep to win even more. I am just happy to have played my part, with the support of my team-mates and the staff.”
SKY