Luiz Henrique da Silva giggles at the question: how do you spot the difference between Rafael and Fábio? The big brother, who came to England to look after the Brazilian twins, seems genuinely puzzled by how, as in the lyrics of the chant that echoes around Old Trafford, when the boys run down the pitch, one can't say which is which. "When they were babies it was hard, and my mom managed to feed Rafa or Fábio a bottle twice," Luiz Henrique says. "But now they are totally different in the way they look and behave."
He observes how Fábio moves his arm oddly when he runs and the chickenpox spots and scars on Rafael's face. But uncertainty remains in the Manchester United dressing room, with even Sir Alex Ferguson confusing the duo. Fábio says: "There was a match where he came to me in the dressing room and started to tell me off, but calling me Rafael. He still gets us confused, but it doesn't matter. Sir Alex knows everything about football and he loves the Brazilian style. He is crazy about Cafu, our idol."
That "style" is another trait the pair have in common, and in terms of ability there is little to separate them. The brothers have been fighting for the same position in the team since Ferguson began experimenting with Fábio, a right-footed left-back, on the side of the pitch for which Rafael was originally signed to occupy. As a result Rafael will likely be sat with the Scotsman on the bench at the start of the Champions League final at Wembley, with Fábio expected to make the starting XI. Rather than sulk, however, Rafael sees half full a glass that until very recently risked emptiness.
"I am happy to see my brother bouncing back after a difficult start at United," he explains. "He got injured a few times and didn't get many games in the first two seasons. There was even talk about him being loaned out. We have been together throughout our entire career and would love to keep it this way for as long as possible."
The 20-year-olds live together at the same house in Cheshire with their wives and Luiz Henrique, who is also married and has a daughter. As well as Brazilian TV channels, the troupe appreciate the expatriated cuisine and the scent of black bean stew can be detected emanating from the kitchen. Carla, Rafael's other half, calls their home the Republic of Silva, with the twins' parents and other relatives from Brazil sometimes spending time there too. "The boys are very quiet in terms of social life," she says. "They say that after all the travelling and training the last thing they want is to go out. Sometimes we nag them a bit and might get to go to a restaurant, but most of the time we are all here."
After three seasons at Old Trafford, the twins feel integrated into the United ethos and praise Ferguson for helping them settle. Even when Rafael's sending off against Bayern Munich in the 2009-10 Champions League quarter-finals cost United dearly, the Brazilian was not on the receiving end of the hairdryer in the dressing room. "He was angry but it was more a paternal dressing-down than anything at full blast. It actually made me feel more ashamed than if he had screamed. But he always talks to us about taking time to learn with our mistakes and not being too anxious."
They are also thankful for Ferguson's comprehension of their bond. "He understood when I went down the dressing room to see my brother after he got hit badly in the head [against Blackpool last January]," says Fábio, who would otherwise have replaced Rafael on the pitch. His familial duty was also tested during a run-in with Craig Bellamy. "Dirty player, always moaning and trying to wind people up. He pulled Rafa's hair once and I wanted to punch him."
Looking after each other was something they learned early on. Sons of working-class parents, the twins grew up in Rio de Janeiro's Peak District, where rich country houses share space with more humble surroundings. Football saved them from menial work, and they are proud of their father's job as a porter in a deluxe condominium. "We are grateful for what he and my mom have done for us," Rafael says. "We didn't have much but were never obsessed with money. I guess that helped us a lot when United came knocking."
They claim to have turned down an offer from Arsenal because it would have bypassed their then club, Fluminense, in the negotiations. "My mum was adamant," Fábio explains. "We could not turn our backs to the club that took us on when we were only 11, even though they then refused to allow us to play in the first team when the contract with United was signed."
The episode is still brought up in the Brazilian media as the twins became a symbol of a new era where younger talent would, as the Portuguese phrase goes, take the airport way. Signed at 16, Rafael and Fábio had previously arranged to play a season for Fluminense so that the transition to the Premier League would not look so daunting, but there was a change of directors and the boys were told by no less than World Cup winner and former full-back Branco that they were surplus to requirements. "Some supporters thought that we were the ones refusing to play but I reckon people understand it now," says Rafael. "If we ever play in Brazil again, we would definitely listen to Fluminense, as much as my brother and I support [local rivals] Botafogo."
The twins ended up as full-backs by accident. In their early days in the Fluminense academy, based in the outskirts of Rio, Rafael's preference for the right side of the pitch had more to do with escaping the scorching heat than beating his marker. "The training pitch had a shadow on the right side and I, then a midfielder, went through there a couple of times during a game so I could escape the sun," he recalls. "The manager liked it and moved me to right-back."
Fábio's journey to the left side was more circuitous. Originally a striker who once fed off his brother's long balls to score goals galore in a local team in Petrópolis (a mountain town near Rio and historically important for hosting the Brazilian emperor's summer palace), at Fluminense he struggled to find a place until the first‑choice left-back was dropped because of forged documentation. "The manager put me there and I ended up enjoying it more than playing up front, as much as Sir Alex sometimes has to remind us that we can't bomb forward as much as Brazilians full-backs do."
On Saturday United will come up against one such player, Barcelona's Dani Alves. The Da Silvas are respectful of the Catalan team but see no reason why they should be apprehensive about sharing the same pitch. "We have a side full of confidence and good players and shouldn't fear Barcelona," Fábio says. Rafael, as he often does, enforces his brother's viewpoint. "I don't see why we can't hurt them if we stick to a game plan where we don't make the same mistakes made by some of their opponents. Basically, Barcelona do not like being attacked or pressured. We need to make them feel uncomfortable."
Our conversation is in Portuguese but the twins' English is not as hesitant as might be expected in their discussion with the photographer. It is good enough to understand a rare joke by Paul Scholes – "He is a quiet guy and nobody expects him to say something funny, but all of sudden he will," says Rafael – and to realise they should not push Wayne Rooney too hard during kickabouts. "Wayne can get quite competitive, but that's why he's such a great player," explains Fábio. Nani still amazes the twins with his tricks and they also admire how Dimitar Berbatov casually executes plays.
In the dressing room Rio Ferdinand has filled the role performed by their brother at home. "He was always joking with us since the beginning, trying to make us relax," says Rafael. No doubt the twins will be similarly supporting each other on Saturday, even if only one can make the starting line-up.