The night the party started
The nicknames were knocked about all day - Fiesta Friday, Vamos Viernes, Fastuoso Friday, Viva El Viernes.
Ten finals, six British medals, personal bests with fat chunks taken out of them and a golden finish for one of the unsung talents of the GB team.
It was one of those frantic, action-packed nights that make a big athletics meet special - track final chasing track final, shocks and surprises coming thick and fast, almost every finish a ding-dong delight.
At one point it looked like being the stuff of UK Athletics chief Charles van Commenee's wildest fantasies. If the failure of the three British men in the 1500m denied him his big climax, it was still a breathless night of cut and thrust.
The caveat that keeps cropping up at these championships is the times and distances. They're too slow or low, or they mean nothing on a global scale, or they're not what they used to be.
To some in the sport it's the stats that matter. To others, it's something more corporeal: nail-biting contests where the outcome is in doubt to the very last moment.
Records are the shock and awe, but close contests are what makes sport gripping. And Fiesta Friday had that throughout.
When Andy Turner surged past a stumbling Petr Svoboda to snatch sprint hurdles gold, it briefly became Four-Letter Friday. "If you can lip-read I apologise," he said afterwards, but no-one familiar with his back-story would begrudge him a little loose lip.
Taken off funding two years ago, battling Achilles problems all season, he is a case-study in hard work and persistence.
"It's been a difficult couple of years, but I love the sport," he beamed. "I had a dream of winning the gold, but it was hard to believe. For all the million downs you have, one up like today makes it all worthwhile."
By that stage, there seemed to be a Union flag on permanent lap of honour. The races and stories were clambering all over each other.
That Christian Malcolm had started things off by taking silver in the 200m was in its way as surprising as Mark Lewis-Francis's medal of the same colour in the shorter sprint, and maybe even more heart-warming.
MLF wasn't the only British sprint wunderkind of the late 1990s. Two years before the younger man took world junior gold, Malcolm went one better and did the 100m/200m double at the same level in such silky smooth style that a golden future seemed assured.
Injuries, loss of form, the abilities of some (Bolt and Gay) and the dubious actions of others (Kostas Kenteris) meant that until Friday his best return as a senior in an individual race was a Commonwealth silver as 19-year-old.
Earlier this year, struggling with injury again and shorn of funding, a European medal of any colour seemed outlandish. That in the end it wasn't quite a gold was hard for him to take.
"I didn't see Christophe Lemaitre; I didn't even hear him come," he said, a head full of what ifs and never weres. "I missed the dip because I really thought I'd got it."
The medals kept coming. Michael Bingham and Martin Rooney made light of tough lane draws to take 400m silver and bronze, only a late Lemaitresque surge from Belgium's Kevin Borlee denying Britain its 10th gold medal in the single lap event.
It was in this stadium 18 years ago that Sally Gunnell stormed to the 400m hurdles Olympic title. The young woman who may yet mature to match her, Perri Shakes-Drayton, ran the race of a veteran to take the first senior medal of her own burgeoning career.
If the surprise bronze was impressive, the even-paced running and tactics spot on, the personal best by almost half a second more than matched them.
PBs in big finals are a happy habit British athletes seem to be acquiring. For Jenny Meadows, it's the same with medals. Her bronze in the 800m, after a summer almost wrecked by injury, completed a splendid hat-trick: bronze at the Worlds a year ago, silver at World Indoors in March and bronze again in Barcelona.
"Three championships, three medals. I'm absolutely delighted," she admitted. "This ranks up with the best - I've had to fight so hard to even be on the start line."
As impressive as the rest, even if she was not rewarded with a medal, was Hattie Dean in the steeplechase. Roared on by Paula Radcliffe in the BBC commentary box, she sliced more than eight seconds off her personal best, and was only denied a remarkable bronze by Lyubov Kharlamova's strength off the final barrier.
Those were the headlines. Season's bests for pole-vaulter Kate Dennison and long jumper Chris Tomlinson were almost lost in the melee.
All the while too, the biggest British hope of all was quietly fighting for the heptathlon high ground. Jess Ennis had expected a battle, but no-one had known that Olympic champion Nataliya Dobrynska would be in such frightening shape.
Ennis is forged of Sheffield steel. In trouble going into her final attempt in the shot put, she produced a life-saver of 14m-plus to salvage the event and then pulled out a season's best in the final discipline of the day, the 200m.
Going into the second day, the scene is set: a lead of 110 points, 44 down on her tally at the same stage in Berlin and with Dobrynska just 26 points down on her lifetime best.
"They're pushing me every way," she admitted. "It's going to be a fight until the end."
What had been missing from these championships was any sign of Spanish success. Nothing gets a party started like early medals for the host nation, but going into Friday Spain had precisely none.
When Marta Dominguez came close to overhauling Russia's Yuliya Zarudneva for steeplechase gold, just as she had at last year's Worlds, the Estadio Olympico came truly alive for the first time all week.
When Arturo Casado went one better and sprinted clear to snatch 1500m gold a few hours later, the fiesta was finally in full swing. With his compatriot Manuel Olmedo in bronze and Reyes Estevez fourth, it brought memories of Fermin Cacho's famous win in the same race in this stadium at the '92 Olympics flooding back.
Each championship needs at least one big set-piece night. Sydney had Magic Monday: Cathy Freeman taking 400m in front of 112,000 of her compatriots, Michael Johnson winning his second Olympic 400m title, Haile Gebrselassie taking the 10,000m from Paul Tergat by a smaller margin than Maurice Greene had won the 100m and Jonathan Edwards sailing out to triple jump gold.
At the Worlds last summer it was Thunderbolt Thursday, when, in a purple patch of 30 minutes, we had the greatest 200m race in history, a fantastic women's 400m hurdles final, a 110m hurdles final where the first three men were separated by a hundredth of a second and a sensational high jump competition that brought 75,000 people to silence and then ear-splitting roars.
If this wasn't quite in the same category, only a cold-hearted curmudgeon could carp. Viernes was very, very good indeed.