Shortly before 4.30pm this Sunday, Jose Mourinho will emerge from the enormous tunnel at the Tottenham Hotspur Stadium and make a beeline straight for the away dug-out.
Pep Guardiola will be there waiting and you can bet your bottom dollar the Sky Sports cameras will be trained on the scene.
But there will be a handshake and an embrace, perhaps a quick chat and mutual smiles. There will be eye contact and genuine warmth and affection to the greeting, then battle will commence.
The once glacial relationship between the two managers who have defined 21st century football more than anyone else has thawed in recent years.
You could say it's a reflection of the way Mourinho's methods of playing the game have gone out of vogue, with his moments of glory now fewer and further between.
While he'd never say it, Mourinho would possibly privately admit that it's the Manchester City boss who continues to have the greatest influence on their coaching bretheren.
And in the week Guardiola's City reached yet another cup final, the gap between the two has never been wider. But it wasn't always this way - and nor was the current cordiality between the pair.
Between 2009 and 2012, when Mourinho managed first Inter Milan and then Real Madrid, and Guardiola was at the helm of a spectacular Barcelona side, their rivalry reached heights of hostility rarely seen between two coaches.
But what is often forgotten is that they were friends before. Mourinho and Guardiola were close when they first met at Barcelona in the 1990s.
Guardiola was coming to the end of his playing career at the Nou Camp just as Mourinho was going through that remarkable transition from Bobby Robson's translator to tactical influencer.
He then served as Louis van Gaal's assistant and Mourinho bought into Barcelona's way of playing, which seems so unlikely given the teams and tactics he produced later.
The pair certainly spent many hours at Barca's training ground chatting about tactics and Guardiola came to respect Mourinho's analytical way of looking at the game.
Things changed in 2008. Mourinho, by this time a serial champion after successful spells at Porto and Chelsea, was interviewed for the Barcelona job following Frank Rijkaard's departure.
In a Powerpoint presentation to Barca officials in Lisbon, Mourinho actually named Guardiola, at that time manager of Barca's B team, as one of his potential assistants.
But sporting director Txiki Begiristain favoured a move for Guardiola and he got the top job. Mourinho certainly didn't forget the snub in a hurry.
With Mourinho rocking up at Inter Milan not long afterwards, it was only a matter of time before their paths crossed in the Champions League.
They were duly paired together in the group stages of the 2009-10 Champions League, with the goalless draw at the San Siro a tactical chess mate and a goalless stalemate, before Barcelona won the return 2-0.
Mourinho admitted afterwards his team had been outplayed: 'We're far from being Barca in terms of individual qualities and profile. They are better than us.
'If you told me that Inter will face Barca in the semi-final, I will accept it already.'
Mystic Mourinho got his wish - the two clubs were drawn together in the semi-finals - and it proved to be his finest hour.
A Barcelona team that had been forced to make the long journey to Milan by bus because of the Icelandic ash cloud went down 3-1 in the San Siro.
Afterwards, Mourinho couldn't resist taking a skeleton out of the closet. His Chelsea team had been beaten by Barcelona in the previous season's semi-final after Norwegian referee Tom Henning Ovrebo turned down four penalty appeals.
'A year ago, Chelsea were crying and Barca were laughing with the referee,' Mourinho scowled. 'They laughed because he denied my Chelsea boys their rightful place.'
His comments could have easily backfired, especially when Thiago Motta was sent off just 28 minutes into the second leg.
But in what would become the classic Mourinho 'park the bus' template, his Inter side restricted one of the best club teams of all time to just four shots on target and one goal to reach the final 3-2 on aggregate.
Nobody will ever forget the way Mourinho sprinted across the Nou Camp pitch, arm raised, to celebrate with his players and the travelling Inter fans up in the Gods.
'It was the most beautiful defeat of my life,' he said. 'It is a style of blood not skill. We were a team of heroes. It's a pity I could not play because I have got the same blood.'
Inter would go on to beat Van Gaal's Bayern Munich to complete a Treble and Mourinho announced after the final at the Bernabeu that he was leaving to become manager of... Real Madrid.
Now things between Guardiola and Mourinho were going to get really claustrophobic.
They were already being cast as the Yin and Yang of football because of their coaching philosophies. Guardiola favoured a possession-based, high-press, attack-minded approach, designed to excite and entertain, and won legions of admirers all over the world as a result.
Mourinho was more of a pragmatist. It was win at all costs, even if that meant stealing an early goal and then putting 10 men behind the ball to soak up opposition pressure. There could also be a needle and a nastiness about his teams.
Both methods worked, however, with both managers enjoying plenty of success throughout their careers. They just went about it in different ways, splitting opinion. For many fans, it was light and dark, good versus evil.
Never was this more apparent that in November 29, 2010 when the two teams met at the Nou Camp in LaLiga and Barcelona annihilated their Clasico rivals 5-0.
'The 5-0 was the best game I have ever played in,' recalled Barca midfielder Xavi. 'The feeling of superiority was incredible - it is one thing to have it against another team, but against Real Madrid? They hardly touched the ball.'
Barcelona were so good they gave themselves a one minute ovation upon returning to the dressing room. Fortunately Mourinho didn't hear this self-adulation, but from then it was war. Mourinho resolved to beat Barca by any means necessary.
He would have his opportunity during an extraordinary fortnight that saw four Clasicos in three different competitions.
A tense 1-1 draw at the Bernabeu in the league was followed by Real winning the Copa del Rey final 1-0 thanks to Cristiano Ronaldo's extra-time goal.
Guardiola was incensed that the linesman had disallowed a goal by Pedro: 'The assistant must have great eyesight to spot that Pedro was two centimetres offside.'
A war of words followed as the two rivals prepared to meet in the Champions League semi-finals the following week.
Mourinho kicked things off with a mocking remark: 'We have started a new era with third group, in which there is only him [Pep], that criticises the referee when he makes correct decisions. This is completely new to me.'
The Portuguese had finally succeeded in getting under Pep's skin and the Barcelona boss hit back in the Bernabeu press conference room of all place ahead of the first leg.
'As Senor Mourinho has called me Pep, I'm going to call him Jose,' began a spiky Guardiola. 'Which one is your camera, Jose? All of them, I suppose...
'Tomorrow at 8.45pm we face each other on the pitch. He has won the battle off the pitch. If he wants his own personal Champions League trophy away from the pitch, let him take it home and enjoy it.
'In this room, Mourinho is the f***ing chief, the f***ing boss. He knows all about this and I don't want to compete with him in here.
'I'd just like to remind him that I worked with him for four years [at Barcelona]. He knows me and I know him.'
Guardiola was given a standing ovation by his players when he arrived for dinner in the team hotel and they did their talking on the pitch, winning 2-0 thanks to two Lionel Messi goals after Pepe had been sent off.
That was the fifth game in succession with Inter and Real that Mourinho had seen one of his players sent off against a Guardiola side. Mourinho was himself sent to the stands for protesting Pepe's red.
Inevitably, Mourinho launched an attack on one of his favourite targets - referees - in one of his all-time great rants.
'One day, I would like Josep Guardiola to win this competition properly,' he said. 'If I tell UEFA what I really think and feel, my career would end now.
'Instead I will just ask a question to which I hope one day to get a response. Why? Why Ovrebo? Why Busacca? Why De Bleeckere? Why Stark? Why?
'Because every semi-final the same things happen. We are talking about an absolutely fantastic football team, so why do they need that? Why?
'Why does a team as good as they are need something that is so obvious that everyone sees it? I don't know if it is the UNICEF sponsorship or if it is because they are nice guys.
'They have to get to the final, and they'll get there, full stop. Josep Guardiola is a fantastic coach.
'But I have won two Champions Leagues and he has won only one Champions League – and that is one that would embarrass me.
'I would be ashamed to have won it with the scandal of Stamford Bridge. If he wins it this year, it will be with the scandal of the Bernabeu.
'Deep down, if they are good people, it cannot taste right for them. I hope one day Guardiola has the chance of winning a brilliant, clean championship with no scandal.'
The score would soon be 2-2 when it came to Champions League wins. The second leg finished 1-1 and Guardiola's team went on to beat Manchester United 3-1 in the Wembley final.
The blue touchpaper was now burning up quickly and even the pre-season Spanish Super Cup saw tensions flare up.
Mourinho poked Tito Vilanova, Guardiola's assistant, in the eye during a furious melee that followed a naughty tackle by Marcelo on Cesc Fabregas.
'Someone has to take action on the matter. Mourinho is destroying Spanish football,' said Barca defender Gerard Pique after Barca won 5-4 on aggregate.
Mourinho was, as ever, only too happy to hit back, suggesting Barca players were soft. 'We intended to play like men and not fall on the ground at the slightest touch.'
But while Mourinho was determined to alwways have the last word, his side were often second best on the pitch. They lost 3-1 at home in the league and then lost to Barca in the last eight of the Copa del Rey.
However, Real were proving an unstoppable force and a 2-1 win at the Nou Camp with four rounds of the season left virtually ensured they would win the title. It was Barca's first home loss in 55 games.
It was at that point Guardiola announced his intention to leave Barcelona and take a sabbatical.
Of course, Mourinho couldn't resist a little dig: 'It's his life, but for me it's unthinkable to take a sabbatical. He is younger than me, but I'm not tired.'
How times have changed. Now it's Mourinho who looks worn out - his methods tired and discredited, his standing within the game diminished. Meanwhile, Guardiola has continued to succeed.
And from all this, a genuine Détente in one of football's bitterest cold wars.