The centre back retains a strong sense of community spirit and tries to give back to causes which can help people worse off than him

Gabriel insists that the two now have a positive relationship

A high-profile incident between them saw Gabriel sent off this season

He has been involved in a couple of spats with striker Diego Costa

The Brazilian has come a long way in his football career

Gabriel laughs, screws up his eyes, shakes his head and then buries it in his hands, in embarrassment.

Diego Costa is the subject. Not the infamous clash at Stamford Bridge last September, which saw Costa feign an injury to get the Arsenal defender sent off, a red card which was later overturned.

This is an earlier clash, with Costa in the colour of Atletico Madrid and Gabriel playing for Villarreal. Costa does swing an arm at Gabriel but it barely makes contact and the Villarreal man collapses to the floor in agony.

Arsenal defender Gabriel has come a long way since his days growing up in an impoverished favela

The 25-year-old centre back signed for Arsenal from Villarreal last January for a reported £11.2m fee

To his credit, he does seem genuinely mortified when it is brought up and looks pleadingly at his inquisitor.

'When we are on the pitch we are different people,' says the 25-year-old centre-half, signed from Villarreal for £11.2million last January. 'Diego is a different person and so am I. When we clash there are sparks!'

Indeed. Both Brazilian born, though Costa has since opted to play for Spain, the country to which he moved to play football, they share a common spirit. Neither is likely to walk away from a confrontation, regardless as to whether it concerns them or not.

The original furore with Costa had been sparked by the Chelsea player barging over Laurent Koscielny. Gabriel wouldn't stand for that and immediately sprung to his team-mate's defence, physically remonstrating with Costa.

To some, it seemed a welcome addition to Asrenal's collective identity, a streetwise fighter ready to go toe to toe with Chelsea; except that he ended up being suckered into being sent off.

'That's how I am,' says Gabriel. 'I will always stand up for the ones I love. We have affection for our team mates because we spend most of our time with them. Sometimes we spend more time with our team-mates than our families. This is my instinct I always stand up for my team-mates.

'For me, the red card was a surprise but I learned from that experience. I won't change. That's how I react in these situations but I learned and I will defend my team-mates but in another way — not doing what I did.'

What he said to Costa is apparently unprintable. 'It was an affectionate exchange!' he says. 'It's something that happens in a football match. It was in the moment.'

Gabriel was shown a red card earlier this season after an altercation with Chelsea striker Diego Costa (left)

Gabriel has since insisted that he and Costa have buried the hatchet and now have a good relationship

Gabriel is donating a day's wages along with his team-mates to the Arsenal Foundation, which supports causes including Save the Children

And it seems they have kissed and made up. Gabriel is now in the Brazilian national squad and shares a mutual friend with Costa in Filipe Luis, the former Chelsea left back. 'We have turned that page.

'I was in the Brazil squad with Filipe Luis and those two are good friends. I sent him a voice message as a friend. We are good friends. It's something that happens on the pitch and it is passed. Diego is a good person.'

However, he rejects any suggestion that Costa, raised in Lagarto, a remote town in the northern Brazilian Savannah, has much in common with him.

'I wouldn't say we are similar just because we came from a poor background,' says Gabriel, who grew up in the Sao Paulo favela of Capao Redondo. 'Really, Sao Paulo is a lot worse than Lagarto!'

Gabriel's remains proud of his community and still contributes financially to the youth football team for which he played there but he does not sugarcoat the experience.

'We didn't have water in our pipes and electricity we took from the mains cables. I've seen many bad things, I was robbed. I've seen crimes.

Gabriel has opened up about his difficult childhood and is grateful to now know his family are safe

Gabriel's rags-to-riches rise has given him a fresh perspective in life and he wants to give back to his roots

'In the beginning it was quite tough, we had to live in such difficult conditions. I had to see things that I don't want to see ever again. It was a violent environment. That situation made me feel stronger to achieve success in football, that's what I always dreamt of.

'I was trying to fight for my family, my mother [Terezinha] was in need at that time. So football was the only way I could help her. I had five siblings [he is the youngest of Jose Marcos, Marcos Antonio, Ana, Paulo, Rafael] and they were all working but I was the only one who could help my mother. I wouldn't say that I suffering from being hungry but it was difficult to put a meal on our plates, to have a proper meal in our house, so football was the only way to help my mother.

'I was privileged, because I'm the youngest kid in my family so when I was born things were better for me. My dad [Silvio] and my siblings used to live in a house made from wood in the favela. They lived in houses like that but I didn't. When I was born we lived in a brick house.

'In my time we just had football and school. Those were the only activities we had to do. We didn't have any other option. It was very difficult, because all of my other friends, they didn't have any options. If you don't succeed in football, you don't have any options to have a life.

'Nowadays it's getting better because the mayor of Sao Paulo built a community centre, so they have dance class, language class, we have music classes. So now the kids they have more options. If they like to dance, they can go there to have classes; if they like football, they have a football teacher for them.

'Today they have more options but in my time we just had football. In my time we had the football pitch without grass, we had a mud pitch.'

Gabriel's early footballing experiences were far more modest than life in the Premier League

Gabriel, in action for Arsenal in the Champions League, dribbles with the ball against Olympiacos

He has since discovered that his Brazilian team-mate and Chelsea opponent Willian often used to play on the same pitch.'

An early trial for Santos didn't work out but a call up for a local team, Taboao de Serra, the Sao Paulo cup and impressive performance against Vitoria saw him move to the top-flight club in north east Brazil, where Bebeto and David Luiz had also played.

Earning good wages though didn't help him escape the violence of his youth, but merely attracted trouble.

'I was robbed when I was young and playing for Vitoria, it was my first professional team. I was withdrawing money from the cashpoint and they followed me on a motorbike and stole my money. It was not my whole salary but it was a lot of money by Brazilian standards.'

He has moved his parents to a house outside Sao Paulo, with kidnapping of relatives an all-too-real fear for South American players.

Gabriel, pictured here during his spell at Vitoria, escapes the tackle of Corinthians' Ronaldo (right)

'When I was in Vitoria it was OK to let my parents live in that community but now I'm playing for Arsenal and I've been called up from Brazil things are more dangerous for my family so now I have bought a house for my family in a different area, outside of Sao Paulo.

'I'm worried about them being kidnapped. It worries me a lot. I'm playing and I need to be focused on football and this was worrying me a lot.'

Yet he maintains his connection with Capao Redondo. 'In my time my football club as a boy we were always getting invitations to play in the countryside around Sao Paulo against the other academies and we never had money to pay for travel expenses.

'So now I pay for the expenses and the fee to be part of the tournament and give them back what they gave me.'

Along with his Arsenal team-mates, he is also donating a day's wages to the Arsenal Foundation, which supports causes including Save the Children, with whom Arsenal are building football pitches in refugee camps in Iraq. 'It's pure joy,' he says.

'As a footballer it is our duty to help people because someone helped us.'

Footballers' endorsements of the charities they support can sometimes feel trite; Gabriel's sounds as if he means it.

Arsenal's match against Manchester City on Monday is dedicated to The Arsenal Foundation.