It remains arguably the most iconic image of Jose Mourinho's managerial career: the Portuguese sprinting down the Old Trafford touchline in 2004 to celebrate with his Porto players.
Costinha's last-minute goal on that March evening didn't just knock Manchester United out of the Champions League, it altered the course of European football.
What's more, it made Mourinho a global star. He had already won the UEFA Cup with Porto a year earlier but this was the moment that the coaching prodigy truly announced himself on the world stage.
By toppling the legendary Sir Alex Ferguson in his own backyard, it was official: the handsome young upstart from Setubal was the real deal.
His already staggeringly high self-belief soared and, just a few months later, after leading Porto to Champions League glory, he would rock up at Stamford Bridge and effectively anoint himself 'The Special One'.
He would go on to end Chelsea's 50-year wait for an English title before later winning a historic treble at Inter and then ending Barcelona's domination of La Liga with Real Madrid.
None of it, though, would have been possible without Costinha's last-minute equaliser at Old Trafford.
And the remarkable thing is that Mourinho had very little to do with it.
In fact, he was furious that Benni McCarthy had stepped forward to hit the free kick that United goalkeeper Tim Howard flapped into the path of Costinha, as Mourinho had wanted Ricardo Fernandes to take it.
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"I remember that in the moment we did nothing that Jose told us to do," Costinha tells Goal. "Nothing we did was a Mourinho plan!
"The coach can prepare you perfectly for games but there are moments when players change things by themselves – and in a good way.
"In that particular moment, we didn't do what Mourinho wanted. We did it differently. But the ball went into the net. Howard had dropped it and John O'Shea was caught ball-watching and didn't react quickly.
"I did, though, and when I scored, I just saw the image of my supporters. I forgot everything in that moment and just went over to celebrate with them. What a feeling!"
Porto's elation was wholly understandable. Few pundits had given them any chance of progressing to the quarter-finals at United's expense.
Mourinho, though, had always believed in his players.
"When we drew Man United, I remember Jose said to us, ‘Let the shark come,'" Edgaras Jankauskas reveals to Goal.
"There was no fear factor that I remember and we won the first game 2-1 with two goals from Benni McCarthy. However, we went to Manchester knowing it would be tough.
"But the pressure was on them: they expected to go all the way to the final and to lose would be a disaster for such an iconic organisation.
"Probably 95 per cent of people thought Man United would find a way through, given they were the better and more experienced team.
"They had players like Paul Scholes, Ruud van Nistelrooy and Roy Keane. They were superstars of the highest level who could beat any team in the world.
"But Keane was sent off in Portugal, so we knew he would be missed in the second leg. We knew we had a chance."
Mourinho knew it, too, particularly as he would once again be able to call upon Costinha, who had missed the first leg through suspension.
The pair's relationship had become strained in the preceding months and they were barely speaking at the time.
However, after Porto were pitted against United in the last 16, Mourinho approached Costinha while the midfielder was stretching at the end of a training session.
"He said; ‘Costa, look at the draw: Manchester United. The first game is at home and the second away.
"'You are suspended for the first game but we will beat them by a goal and then, you will be there in the second game when they will press us.
"'Long balls, duels and you will put them out of the competition.’ He then stood up and left.
"What else can I tell you about Mourinho? He was right: that’s exactly what happened.
"He always gave us the right input at the right time. He managed our mentality perfectly. He always kept us focused.
"Even when I was talking to an Italian club at the time, he called me in the hotel afterwards and he said; ‘Costa, stay with us, we are going to win the league and the Champions League. Then, you can go to England or Italy.’
"He always talked to you like that. And you believed him and it made you more confident. So, we went into matches with more belief than we would have normally had."
That belief only grew after the 1-1 draw at Old Trafford that saw Porto progress to the quarter-finals 3-2 on aggregate.
"When I think about that game, I just remember the last few minutes because it felt like an eternity," Jankauskas admits.
"We knew Man United were strong at the end of matches, always scoring in injury time and they went all out. But we stayed strong, managed not to concede and qualified for the next round.
"We knew then, after beating United, that we could beat anyone. It was at that point that everyone was sure we would get to the final."
And they did, eliminating Lyon and Deportivo La Coruna before routing Monaco 3-0 in the tournament decider to claim just their second European Cup.
Mourinho admitted that night in Gelsenkirchen that he was bound for England, where he would break a plethora of records with a formidable Chelsea team.
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Of course, it would have been all very different had Costinha not propelled the coach to the forefront of Roman Abramovich's mind with his decisive strike two months previously in Manchester.
Indeed, the Russian billionaire had been considering hiring Sven Goran Eriksson to replace Claudio Ranieri as manager when Mourinho suddenly emerged as the most exciting young coach in Europe.
"No doubt, it was a life-changing moment in his career," Jankauskas says. "I don’t know if he would have ended up there without winning that Champions League title.
"At the time, he was just a young manager of a club that was not widely known. We weren’t even a favourite in the UEFA Cup the year before!
"But under Mourinho we won every European title possible and that's why he attracted the attention of the big clubs.
"He did that not only through his success on the field but also through his interaction with media and television. His personality became very attractive to teams."
It also endeared him to his players, many of whom remain on excellent terms with Mourinho, including Costinha.
"When he was at Real Madrid, he left me tickets at the box office with a note inside," the former Portugal international reveals.
"It was a drawing of him making the movement down the touchline at Old Trafford and he wrote ‘You made everybody stronger that night.’"
Perhaps Mourinho most of all.