If they were not such firm friends, it would be easy to imagine Mathieu Flamini like a cartoon villain hiding behind a tree waiting to stick out a leg and trip up his neighbour, Cesc Fàbregas, as he puts the bins out. Fàbregas is a man that needs halting for any opponent of Chelsea these days, and it is undoubtedly going to be a strange experience this weekend for him to come up against one of his oldest friends in football, the man who once ran like a dervish to give him the platform to pull the strings. In their youth they were quite a double act as a pair of tyros with complementary qualities in Arsenal’s midfield.

To this day, they remain close. They live nearby, bump into each other frequently and speak often. Contemplating whether Flamini will be relishing the chance to harass Fàbregas at Stamford Bridge, Arsène Wenger breaks into a warm smile: “I wish!” he says. “They are always together. Certainly there is that little bit of pride that comes into it when two friends play against each other. He will be keen to stop him.” As most Premier League opponents know all too well, though, that tends to be easier said than done.

Seeing the pair of them in close proximity evokes memories of what might have been for Arsenal. They were allies in the the squad that reached the Champions League final in 2006, playing with 10 men and losing out narrowly to Barcelona. Two years later, they were a central force fuelling the team that was probably the nearliest of nearly men Wenger has assembled in the last decade. “We had such a strong team,” recalls Flamini.

The image that crystallises so much of what Wenger was driving at in the shape of a third successful team at Arsenal is of a 20-year-old Fàbregas running wild at San Siro. He sprinted as fast as he could, so pumped with adrenaline, until he reached the half way line and leapt into Wenger’s arms.

That was March 2008. The run was in celebration of a fizzing strike from 30 yards to put the defending European champions at the time, Milan, out of the competition. It was a team being remodelled on youth, post-Henry, post-Bergkamp, post-Vieira. Somehow, with an air of the miraculous, this inexperienced Arsenal were top of the table at home. Then they threw the Milan of Maldini, Pirlo, Kaká and all an unexpected uppercut. Wenger predicted they would achieve great things.

At the time, the young Fàbregas described that goal in San Siro as one of the best moments of his footballing life. “I went straight to the boss because without him I would never have had the chance to play in a game like this,” he enthused.

Fàbregas was flanked in midfield by two other youngsters. Abou Diaby, who had the qualities to develop in the style of a Yaya Touré – imposing, powerful, elegant and technically gifted – was 21. Flamini, buzzing around hungry to do the dirty work, was 23. “I love playing for this team. We are a new generation, we have to create a new history. There is no limit to how far we can go,” suggested Flamini back then. Trophies, added Fàbregas, were “on order”.

But they never came. The 2007-08 season unravelled. All that promise was punctured. Arsenal’s predatory striker, Eduardo da Silva, suffered a harrowing injury, results dried up. That moment in time in Milan came to represent promise that was never fulfilled.

Flamini calls his second spell at Arsenal “unfinished business”. While he attends to that, Fàbregas writes a new chapter at Chelsea. Diaby, meanwhile, beats his own path trying to find enough fitness to salvage a career shackled by injury. He has clocked up less than 90 minutes of Premier League football in the past 17 months. He is not available for the old boys’ rendezvous at Stamford Bridge.

Flamini says that seeing Fàbregas in blue is strange. But then again, looking back, he laughs as he recalls how the Spaniard attempted to persuade him to stay at Arsenal in the summer of 2008 while he was being courted by Milan. “Of course, he tried,” Flamini says. “But I respect his decision to come back to England and play for Chelsea, just like he respected my decision to leave and join Milan. In football it’s not always easy to make decisions. He is doing very well with Chelsea and I am not surprised.

“We are really close. We stay in touch all the time. He is someone I really appreciate on the pitch, not just because he is a good player but he is a top guy off the pitch as well. It is a special game for me to play against him. I came here when I was 20 and he was couple of years younger. In that time, we’ve experienced a lot. We played in the Champions League final together. And I’ve been fighting for him for many years.

“When we were together here we had a great partnership on the pitch. The difference on Sunday is that I will probably mark him and that will not be easy, first of all because he is a good player but also because he is a friend.”

Ultimately, though, all personal sentiment will be secondary to the vital instincts of coping with the opposition as a whole. Flamini is desperate for Arsenal to put right the humiliation suffered six months ago at Stamford Bridge when they were beaten 6-0.

“We don’t want to make the same mistakes that we made last year,” the Frenchman stresses. “We can’t be two down again in 10 minutes because it is important to stay in the game.

“We have learned from our mistakes. We gave the right example at Everton when we were 2-0 down but managed to come back to 2-2 when we lost 3-0 there last year. We just have to go to Chelsea with the right mentality.”