The crowning glory of the celebrations came when the club captain, Gabi, fresh from enjoying a deliciously slow, stuttering, open-topped bus tour from the Vicente Calderon Stadium, scaled the central statue of the Roman sea god to affix a flag to his trident and a red-and-white scarf around his head.
The cheers were deafening. Atletico's infectious head coach, Diego Simeone, proclaimed that "Madrid is red and white".
Amid the exultant scenes, Koke, the midfielder who has played such a sizeable role in this most inspiring club's triumphant season, took a private moment in which to drink in the scene.
He has grown up in a Madrid dominated by the all-white strips of Real, the era of the 'Galacticos' and the estimated £1bn that has been spent since Hampden and Zidane in 2002 to bring that famous club to the point it reaches in Lisbon tonight: the prospective capture of La Decima, their 10th European Cup.
How sweet it would be for him to dash the dreams of his greatest rivals and achieve everything he, in turn, has dared to fantasise about since the day he joined Atletico's youth academy at the age of eight and embarked upon his long and colourful journey towards the most remarkable week of his 22-year-old life.
Koke - his real name is Jorge Resurreccion Merodio - has become accustomed to seeing his side live in the shadow of their big-spending, more illustrious neighbours. Things are changing, though.
Children now ask their parents for red-and-white striped shirts rather than those of Los Merengues. It is a trend Koke is beginning to see more and more around the streets of his home town.
Should they win tonight's historic meeting of the Madrilenos in Benfica's Stadium of Light and become European champions for the first time, the likelihood is that the footballing face of the city will alter just that little bit more.
Koke will not be anywhere near Neptune for the latest proposed round of festivities, of course, but he can just imagine what fresh mayhem will break out around his feet should Simeone's men complete this most unlikely of doubles.
"Back when I was at school, there were many supporters of Real Madrid," he recalled. "At my school, it was a very small number following Atletico and now look.
"That is important to us. It is a matter of pride for me that they wear their football shirts and a great moment. I fought hard to get here. I struggled for many years from a young age to make it to the first team and achieve all these things.
"I can identify with any guy who is in the ranks, fighting for a dream. Thank God I have just been able to fulfil mine. You always dream of winning it all with Atletico, but it becomes more complicated when it becomes real. I have been so lucky. I just hope we can go on to win the Champions League too."
Of course, the mind games started several days ago. Real Madrid defender Sergio Ramos has suggested Atletico should be considered favourites, bearing in mind their capture of the league championship. He insists there is no pressure whatsoever on his side.
Such remarks, for the record, ought to be taken with a shovelful of salt. La Decima has become an obsession with Real's president Florentino Perez and failure is now almost unthinkable. Real operate on a budget over four times that of Atletico and there has to be compensation for the team's spectacular collapse towards the end of the Primera Division campaign.
"They are the favourites, having such a large staff and all that money, but we will play with our humility, our heart and our will," stated Koke.
"It will be a close game, in which you will have to fight like it's the last game of your life."
That warlike spirit is most certainly something the combative Simeone, a league champion with the club as a player, has instilled within his squad over the course of the last two-and-a-half years.
When the Argentinian coach, bidding to become just the third non-European manager to win the European Cup after compatriots Luis Carniglia of Real Madrid and Internazionale's incomparable Helenio Herrera, took over at the Vicente Calderon in December 2011, the team was 10th in the table and had just been knocked out of the Copa del Rey by Albacete.
He has since won the Europa League, the Copa del Rey, the UEFA Super Cup and the title. Simeone has also developed a great affection for the local rivalry with Real and clearly relishes filling the role of underdog.
"The rivalry is great, both in terms of the matches themselves and the fact that, in one city, you have such a powerful team as Real Madrid and a battling team such as Atletico Madrid," he said.
"The idiosyncrasies of the clubs couldn't be more different, possibly from a social perspective as well. Each team uses the tools it has at its disposal and it's a great rivalry, no matter which team you support."
Tonight, Atletico will use their recent source of inspiration to try to carry them to one last, great, glorious effort.
Luis Aragones, the European Championship-winning manager of the Spanish national team, scored for Atletico in their last European Cup final in 1974 when they let their one-goal lead slip at the end of extra-time and lost 4-0 in a replay.
He died at the beginning of February and has been such a driving force behind Simeone's team that the coach stated he must have been defending with them towards the end of the 1-1 draw in Barcelona that sealed the league title.
Aragones' name will be sewn into the collar of every Atletico player's shirt tonight and the solidarity that has been the foundation stone of this season will be called upon again.
"The unity of the group is the key to everything we have achieved," said Koke.
Atletico looked like they would be without top scorer Diego Costa after he limped out of that match in Camp Nou with a hamstring tear early in the first half, but he has miraculously returned to training after being treated in Belgrade using horse placenta.
Arda Turan, the side's Turkish playmaker, has also joined in with the last couple of sessions after suffering a hip knock on the final day of the league campaign.
For Real, Cristiano Ronaldo and Gareth Bale will both be fit with defender Pepe and striker Karim Benzema pushing to be part of the squad.
"It is a moment that all Madridistas are dreaming about - the decima," stated Ronaldo.
"Real Madrid have wanted it for a long time. Since the first day we came here, we've felt that positive pressure to win the Champions League. We feel like we are now one small step away from winning."