This wasn’t supposed to happen. Not in a Champions League dominated by the same familiar faces, by the superpowers and the Premier League’s moneyed elite. Not for the club who sold Jude Bellingham and Erling Haaland or the team many expected to perish in the group of death or the side who blew the Bundesliga on the final day of last season. Not for Edin Terzic, the nice-guy manager who has spent parts of his reign seemingly in danger of being replaced.

But Borussia Dortmund are in the Champions League final. Perceived as the weakest side in the last eight, seen as the outsiders in the semi-finals, they will now be underdogs at Wembley on 1 June. They have got there against the odds – financial and footballing – but with an ethos that makes them look an outlier in the 21st century. This was a triumph for the people’s club against the Qatari project as well as yet another missed opportunity for Paris Saint-Germain, who find new ways to not win the Champions League.

The heartwarming stories instead belonged to the visitors. To the boyhood supporter Terzic, who joins Ottmar Hitzfeld and Jurgen Klopp in taking Dortmund to a Champions League final. To the match-winner Mats Hummels, a survivor of the 2013 final, a player who admitted he thought his last chance of reaching another had gone. To the departing Marco Reus, whose final game for Dortmund will be the biggest of his life. To Jadon Sancho, too, whose season involved four months training with the Under-18s at Manchester United and could end with the most prestigious medal of all.

So much for the supposed predictability of the Champions League. Kylian Mbappe will have to go to Real Madrid to try and win it. There will be no fairytale farewell in the colours of his hometown club. Mbappe and co were denied a goal by Dortmund, though they may long wonder how.

Fortune scarcely favoured them. They struck the woodwork six times across the tie, four of them in Paris. They had 45 shots over the two legs, 30 of them in France. After a host of misses in Germany last week, there were further cases of poor finishing. Yet there were even more instances of wonderful defending. PSG encountered a yellow wall: not the huge bank of fans in the Signal Iduna Park but a defence in which Hummels and Nico Schlotterbeck were outstanding.

Terzic got his tactics right, too. When PSG mounted an onslaught midway through the second half, he brought on Niklas Sule as a third centre-back. Part of the plan at the start involved doubling up on the flanks: Sancho was charged with helping Julian Ryerson against Mbappe, for instance.

And while Dortmund were long known for their heavy-metal football, they instead had a defensive structure behind the ball. This was about patience more than pressing. It required a rearguard action, bodies in the box blocking shots. But Dortmund were willing. There is a resilience and a resolve to a team with a lone defeat in their last 11 Champions League games. This was an epic triumph of teamwork.

Ultimately, PSG could rue their ineffectiveness before the break when the brightest opening came Dortmund’s way: Karim Adeyemi, with Mbappe-esque speed, embarked on an electric burst, scything through the hosts’ defence before Gianluigi Donnarumma blocked his shot.

The goalkeeper was helpless, though, when Dortmund struck five minutes after the interval. An unmarked Hummels headed in Julian Brandt’s corner. Only one footballer has ever made more appearances for Dortmund than Hummels. Now few have scored a more important goal.

It gave PSG an added reason to regret a miss: just before the climactic moment, Warren Zaire-Emery hit the outside of the upright from close range after Goncalo Ramos had somehow hooked the ball in his direction. The teenager probably should have scored, the same upright was then rattled in rather different fashion, when Nuno Mendes drove a 25-yard shot against the post.

Having hit the post twice, PSG had another unwanted double when they were twice denied by the bar. Once again, the first effort was more wasteful, the second struck cleaner. Mbappe miscued an effort that Gregor Kobel did wonderfully well to tip onto the woodwork. Vitinha unleashed a ferocious effort from long range but with the same outcome.

PSG could reflect on the moment when Ramos skied a shot after an hour. He was soon substituted as Luis Enrique reshaped his attack. Kobel saved from Mbappe. In injury time, he claimed a penalty. But his European career with PSG only had minutes to run.

Dortmund, exhausted but ecstatic, saw their unexpected run carry them to the Champions League final and perhaps to a glory that would be all the greater because it really wasn’t supposed to happen.