I helped Ruben Dias turn into Man City machine - he changed in 12 weeks

Ruben Dias made an instant impact when he joined Manchester City at the age of 23.

Making his debut at Elland Road after just one training session, the £64m signing barely missed another game all season with his fitness and performance levels unrivalled. Transforming a backline that had wilted in the previous campaign, Dias's all-action displays with his signature diving blocks made him look like the Vincent Kompany replacement Pep Guardiola had been crying out for.

Now entering his fourth season at the Etihad, Dias has cemented his reputation as one of the best defenders in Europe while his personal fitness regime has pushed the boundaries of what City's staff thought possible. All of which makes it surprising to hear that when he was 17 there were serious concerns about the physical side of his game.

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Francisco Oliveira had known Dias since he was a nine-year-old boy through his Gimnobody gym in Lisbon when he started to come along to karate classes, and eight years later he started individual training sessions. One of the academy directors at Benfica was happy enough with Dias's footballing ability but worried that he was too skinny and not physical enough for the demands of the modern game.

Dias put his all into the extra work - too much to begin with - as he discovered the benefits of the gym for his game. As he came to see improvements, his love for this side of his fitness grew.

"When he started with me, that wasn't at all the case but he started gaining that as he started to see results," Oliveira told the Manchester Evening News. "After