For anyone who has been asleep over the past dozen years: a club called RB Leipzig will play in the Champions League semi-finals. They will not merely make up the numbers but, in many ways, the numbers make them. Before May 2009, there was no team bearing the name. Now they are managed by a 33-year-old and they have, just as they intended all along, gatecrashed Europe’s biggest party with a goal from an American who turned 21 on Valentine’s Day. Tyler Adams is everything Red Bull had imagined when the idea of adding a German club to their global empire became real. He has been part of the system since the age of 12, coming through their New York operation before making the leap to Leipzig last year. In 27 appearances he had yet to score but then, finding space in a stretched finale to what had been a largely draining encounter, that changed in history-altering fashion. Atlético Madrid had looked the likelier winners after equalising through a penalty from their own tyro, João Félix, whose introduction had sparked an otherwise dreary performance from the three-times runners-up. Yet Leipzig had been the ones playing with precision and, when Marcel Sabitzer released the left wing-back Angeliño with a delicious outside-of-the-boot pass, it was fair to assume what happened next would have a point to it. Sure enough, Angeliño showed presence of mind in cutting the ball back while four defenders and two forwards hared towards the six-yard box. It meant Adams, who had been summoned from the bench after Atlético’s goal, had space to take aim from 20 yards. Maybe his daisycutter would have sneaked inside the far post; maybe not. A deflection off Stefan Savic, leaving Jan Oblak with no chance, meant we will never know and nobody in Leipzig’s colours was about to concern themselves with the scruffiness of the finish. The old dog had been rendered lame by a set of new tricks that may also signify a changing of Europe’s guard. Once it was Atlético, gnarled punchers who kept bouncing back from the ropes, who ground their way to the top when eyes were largely elsewhere. Here Leipzig gave at least as good as they got physically, the brilliant centre-back Dayot Upamecano rendering Diego Costa mere dust when he was not marauding upfield or prompting attacks from deep, but also offered so much more. They were slick, structured, smart, stylish when the situation allowed, even if this was far from their most eyecatching display. It was Leipzig, whose precocious manager, Julian Nagelsmann, could probably name his price if one of the established elite called next week, who played with the clarity that suggested they wanted to win through wit and invention. At the outset it seemed they would need those qualities in bundles, given Timo Werner’s early departure for Chelsea. He was replaced up front by the strapping Yussuf Poulsen, who is the nearest thing Leipzig have to a historic totem. Poulsen joined in 2013 as arguably their first “statement” signing, when they were still a third-tier club. He sliced one second-half shot comically out of play for a throw-in but it would be a stretch to say Leipzig were poorer for his presence. Instead they got to work and trusted in their methods. Marcel Halstenberg, the left-side centre-back, should have volleyed them into an early lead and they were the better side in an increasingly attritional first half. Nagelsmann has ensured they are easy on the eye without being gung-ho: Atlético were allowed territory but, more often than not, knew little of how to use it. When the La Liga side showed some penetration, José Giménez had a header blocked and then watched as Saúl Ñíguez tumbled under a challenge from the Leipzig goalkeeper, Peter Gulacsi. Simeone screamed blue murder on the sideline and made his own signal for a VAR check, which eventually decided there was nothing doing. Before Félix eventually did win a penalty, Renan Lodi had been booked for an egregious dive under Upamecano’s challenge. Leipzig were no angels, as three yellow cards would impart, but nor did they resort to anything like that. Their first goal, which mercifully opened up the game five minutes after half-time, was a beautifully-angled header on the run by Dani Olmo after another meticulous move had let Sabitzer cross from the right. A desperate challenge from Lukas Klostermann, a relative old-timer like Poulsen, on Félix led to the leveller for Simeone’s team but that aberration was among their few frayed moments. Félix, the £113m signing who has had a mixed first year at Atlético, might wonder under which of these setups he may best fulfil his potential. There is no chance of Leipzig, whose recruitment model stands far above most, shelling out fees like that. Nor is there any suggestion, after such a seismic match, that their approach is close to reaching its ceiling.