Singing and dancing Atletico Madrid fans poured into the Spanish capital's centre on Wednesday cheering their second Europa League trophy in three seasons.
Men, women and children packed the main tree-lined avenues leading to the central Neptuno fountain, a stone statue of the god of the sea that is the club's home for victory parties.
"We are so happy to win the final. This is a great day for us," shouted Rafa Guijarro, 42, after their 3-0 win over fellow Spaniards Athletic Bilbao in Bucharest.
Several thousand fans in red-and-white striped team shirts joined the party in the warm night air, crowding the square and chanting: "Champions! Champions!".
A group of hundreds jumped up and down together in the street. Some fans climbed lamp posts to see the scale of the party.
A line of riot officers backed by half a dozen blue police vans blocked many hundreds of fans from approaching close to the fountain, which was protected by steel barriers.
The police action sparked howls of protest that rival Real Madrid fans had been allowed to celebrate sealing their Spanish league win May 2 at the Cibeles fountain just a few minutes' walk away.
Late into the night, fans set off bangers and car drivers streamed through Madrid's streets beeping horns as their passengers waved club flags and scarves through windows, leaning out to scream victory.