"By the second or third corner I turned to Luís Figo and said: 'Forget it, mate. You're on your own'." Míchel Salgado starts laughing. Real Madrid's former right-back won't forget that night at Camp Nou in a hurry and nor will anyone else: 23 November 2002 produced arguably the defining image of the Barça–Madrid rivalry. "I used to offer Luís the chance to take the short corner, drawing up close to him near the touchline, but not this time," Salgado explains. "Missiles were raining down from the stands: coins, a knife, a glass whisky bottle. Johnnie Walker, I think. Or J&B. Best to keep away. Short corners? No thanks."
"And then," Salgado says, "I saw it."
There it was, staring up from the Camp Nou turf: a cochinillo, the severed head of a suckling pig, secreted into the stadium and sent sailing Figo's way. "In the dressing room afterwards, we were laughing about it," Salgado remembers. "A pig's head! How the hell did someone bring a pig's head in? What was going through his mind? It was probably the weirdest thing I've ever seen, but then that's the clásico. I remember telling David Beckham: 'You've never seen anything like it.' And he hadn't. It's hostile and bitter, political, territorial. Much, much more than a football match." Especially when Figo was around.
After the game, the Barcelona director Gabriel Masfurrol accused the Madrid media of making the whole thing up with the help of a cunningly concealed cochinillo in the camera bag, while the presidential adviser José María Minguella argued: "We don't even eat cochinillo in Catalonia." Marca and AS reacted fast, publishing additional pictures and stories from behind the cameras. AS's photographer was "disgusted", Marca's found it "pretty funny" and a week later they interviewed the King of the Cochinillo, a chef from Segovia who described it as "an insult ... to the pig."
That was Figo's third season at Madrid since leaving Barcelona and there was no sign of the hatred or the hurt subsiding. When he had turned up at Camp Nou the first time, the noise was deafening. Banners were hung round the stadium. Traitor. Judas. Scum. Mercenary. Figo came out and reached for his ears, twisting them inwards. It was loud. Thousands of fake 10,000 peseta notes had been printed, emblazoned with his image.
"I must be one of the very few sportsmen to have had to perform with 120,000 people against me – and focused on me, not the team," Figo says, when I meet him for FourFourTwo. There's a kind of wistfulness as he says so, a sadness too. Every time he got the ball, the noise rose, insults and missiles flying.
Oranges, sandwiches in tin foil, bottles, cigarette lighters, even a couple of mobile phones. Figo was awful, Barcelona victorious, the match finishing 2-0. "The atmosphere," admitted Madrid's president Florentino Pérez, "got to us all." "That night when Figo first went back was incredible," says Iván Campo, "I've never heard anything like it. Luis didn't deserve that. He'd given his all for Barcelona. It was built up before: 'a traitor's coming', the media said. No, Luís Figo is coming, one of the greats for you. That night hurt him, you could see. His head was bowed and he was thinking: 'bloody hell, I was here last season ...' But my lasting emotion was admiration: you've got balls."
In that first season, Figo hadn't taken the corners at Camp Nou and in the second he didn't play because of an injury some thought a little too convenient but his absence didn't prevent more missiles, including a cockerel's head. In the third, they were waiting for him. Every time he came within range, beer cans, lighters and bottles flew, golf balls too. "I was worried that some madman might lose his head," Figo says. Some madman did. And so did a pig.
Midway through the second half Madrid won a corner. Amid a shower of flying objects, it took Figo two minutes to take it – and then he nearly scored, the goalkeeper Roberto Bonano tipping away an inswinger. Another corner, over on the other side. As Figo strolled across he slowed to pick up the missiles and as he prepared to take the corner he swept the turf of debris, at one point reaching for a bottle of cola, giving an ironic thumbs-up and smiling. Every time he began his run-up, something else landed and the ritual was repeated over and over – stop, pick it up, start again – until the referee Luis Medina Cantalejo suspended the game.
It was held up for 16 minutes and, in the midst of it all, someone spotted the pig's head. "I didn't see it. If I had I would have eaten a bit: an aperitivo!" Figo jokes. "It never even enters your head that someone could go into the stadium with a cochinillo. Or a whisky bottle. That's not sport; I understand rivalry and that goes beyond it. I've played Juve–Inter, Inter–Milan, and the world doesn't come to an end."
"Figo provoked the fans," moaned the Barcelona coach Louis van Gaal. "He walked over to the corner slowly, picked up the bottle slowly, went back to the corner slowly ... and all this consciously and deliberately, without the referee doing anything." And Barcelona's president Joan Gaspart added: "I'm not trying to justify events but Figo's provocation was out of place and totally unnecessary. I won't accept people coming to my house to provoke."
Provoke? By taking corners? Gaspart's emotional reaction showed how hurt he'd been and how hurt he still is: few suffered as he did. The Portuguese's departure was Gaspart's destruction and a decade on he still insists: "Figo walked all the way round the back of the goal. When does a player ever do that? And they weren't trying to hit him. If they had tried, they would have."
Figo became the new focus of the Barça–Madrid rivalry, its physical incarnation, a cartoon baddie in Barcelona's world. His move to Madrid was huge because Figo was huge. The winner of the Ballon d'Or in November 2000, his transfer to Madrid and performances since arriving may well have earned him some extra votes but he'd basically won the award for what he did for Barcelona; it was there that he became the best in the world.
Barcelona had lost a brilliant player but it was not only that Figo had been the best, it was that he had been so reliable, so committed. A famous photo shows him in full Barça kit, posing inside the emblematic Palau de la Música; he'd been introduced to the city by Pep Guardiola, and he had celebrated his last success by dying his hair blue and claret and chanting: "White cry babies, salute the Champions!" Fans sang: "Don't stop, Figo, Figo, keep going, keep going!" and he did exactly that. As one player puts it: "our plan was simple: give the ball to Luis. He never, ever hid."
While he was at Barcelona, a biography of Figo was published by the Catalan newspaper Sport. It was called Born to Triumph and Guardiola wrote the prologue, which reads almost like a love letter. Guardiola opens by placing himself on a flight to Prague in the Champions League. Figo is suspended, "staying behind in your adopted city, the one you love so much", and in his absence Guardiola pens an ode. "We know you're always there [for the team]," he writes before comparing Figo to Diego Maradona.
The biography was published in April 2000. Within three months, Figo had joined Madrid. One former Barcelona player dismisses the complaints of supporters who, he says, can never see football the way players do, insisting "of course Figo went: for that kind of money any player would go". But Michael Laudrup, who made the same journey six years earlier, is quick to differentiate the two cases and one of Figo's team-mates at Camp Nou is equally adamant that this was different: "The lie," he says, "hurts more than the fact."
Ask Figo and the uneasiness is still there, even now. The hint at something beyond his control. Why did you leave Barcelona and join Real Madrid? He sits on a sofa in a hotel in north-eastern Madrid and thinks. "I felt that the directors didn't give me the recognition I felt I deserved," he says. "I told them that, I was clear about it, and they took no notice. They thought I was bluffing. And then things started taking the direction they took. It was uncomfortable because there were doubts and difficult moments. Maybe it wasn't very, very, very clear because it didn't depend only on me."
Did you want to go to Madrid really?
Figo doesn't say yes; what he does say is: "It started with a calentón and it ended up being real." A calentón is a moment's hot-headedness, a spark of anger.
"But in the end it was the right decision," he continues. "I go back to Barcelona and there's no problem. I have nothing against Barcelona and barcelonismo."
Real Madrid were immersed in presidential elections, called by the incumbent Lorenzo Sanz. His challenger, Florentino Pérez, was one of the richest and most powerful men in Spain. But few gave him a chance of winning the presidency: Sanz had, after all, delivered two European Cups in three years after a 32-year wait.
Pérez, though, had an ace up his sleeve. The news broke on 6 July while Sanz was at the wedding of his daughter, Malula, to Míchel Salgado.
Pérez had struck a deal that would take Figo to Madrid if he won the election. In Spain, every player has a cláusula de rescisión – an official price at which his club is obliged to sell. The money is deposited with the league and the "selling" club can do nothing to prevent a departure. The cláusulas are set prohibitively high – Leo Messi's currently stands at €250m while Cristiano Ronaldo's is €1,000m – are largely symbolic and never apply when a sale is agreed. But while Barcelona would never agree to sell Figo to Madrid, Pérez had spotted an opening: negotiations over his new contract with Barcelona had stalled and his buy-out clause, set when he had signed his previous deal, remained 10,000m pesetas, around £38m. That meant a new world record but it was just within reach.
Pérez offered Figo a guaranteed 400m pesetas (£1.6m) just to sign an agreement legally binding him to Madrid in the seemingly impossible event of his election victory. If Figo broke the deal, he would have to pay Pérez 5,000m pesetas in compensation. If Pérez lost, Figo kept the cash and stayed where he was. To Figo's agent, José Veiga, and to Paulo Futre, the former Atlético Madrid player who acted as an intermediary, it looked like money for nothing. It might also help twist Barcelona's arm when it came to the new contract. What's not clear is whether Figo explicitly authorised Veiga to deal with Pérez. Read his words again: it didn't depend only on me.
When Veiga confirmed the deal, the impact was nuclear. Figo denied everything, insisting: "I'll stay at Barcelona whether Pérez wins or loses". He accused the presidential candidate of "lying" and "fantasising".
He told Luís Enrique and Guardiola he was not going and, relieved, they conveyed the message to the Barcelona squad: relax, Luís is staying. Maybe he hoped he was: Futre has claimed that Figo was furious with him and the way Figo spoke in the media suggested a man trying to torpedo Pérez's chances, just in case. On 9 July, Sport ran an interview in which he said: "I want to send a message of calm to Barcelona's fans, for whom I always have and always will feel great affection. I want to assure [them] that Luís Figo will, with absolute certainty, be at Camp Nou on the 24th to start the new season." He added categorically: "I've not signed a pre-contract with a presidential candidate at Real Madrid."
Sanz was delighted, joking: "maybe Florentino will announce that he's signed Claudia Schiffer next." But on 16 July Pérez, who had carefully been rounding up postal votes too, was named Madrid's new president with a 3,000-vote margin.
Barcelona were also going through elections, the former vice-president Joan Gaspart emerging as the winner a week later. His first task was to manage the crisis. He claims that Figo pleaded with him to block the move to Madrid: the winger did not want to leave but the clause was watertight. Veiga had been outmanoeuvred and was now cornered, pressuring Figo into leaving and even going so far as to turn on the tears. Gaspart says Figo told him his agent was "suicidal" with worry.
The only way Barcelona could rescue Figo from Madrid's clutches was to pay the penalty clause: 5,000m pesetas, just under £19m. That would have effectively meant paying the fifth highest transfer fee in history to sign their own player. Raising the money was one issue but there was another problem too, according to Gaspart: "To convince the socios that the Figo deal was real, Florentino had promised them they would go free for a year if he didn't sign. How? By financing that with the 5,000m pesetas [penalty] we would have to pay on Figo's behalf. I couldn't do it. I'm the new president of Barcelona and I pay for Real Madrid's fans to watch them every week? I would die ... die!" There was no way out. After final conversations between Gaspart and Figo had resolved nothing, Barcelona's new president called the media and told them: "Today, Figo gave me the impression that he wanted to do two things: get richer and stay at Barça."
Only one of them happened. The following day, 24 July, Figo was presented in Madrid, handed his new shirt by Alfredo Di Stéfano. His cláusula was set at 30,000m pesetas. "I hope to be as happy here as I was at Barcelona," he said, barely smiling. "Figo was born to play for Madrid," Pérez later insisted. Gaspart vowed: "I won't forget this. Whoever's responsible will pay."
• Fear and Loathing in La Liga: Barcelona vs Real Madrid by Sid Lowe is published now by Yellow Jersey Press. To order a copy for £15.19 (RRP £18.99) with free UK p&p, visit theguardian.com/bookshop or call 0330 333 6846