What in the wide world of sports just happened?

Champions League drama at its finest (and zaniest), that's what.

Borussia Dortmund advanced to the UCL semifinals with a 4-2 victory over Atlético Madrid (5-4 aggregate), while PSG got past 10-man Barcelona 4-1 (6-4 aggregate).

Below, we'll break down the winners and losers from two of the most bizarre and compelling matches of the season.

Winner: Dortmund's Finishing

What a performance from Dortmund.

Needing to win to advance, the German side jumped out to a 2-0 lead behind goals from Julian from Julian Brandt and Ian Maatsen.

But in typical Dortmund fashion the lead dissolved, as the back line couldn't preserve the advantage.

The side wasn't to be denied on this day, however, as Niclas Füllkrug and Marcel Sabitzer provided the crushing blows to Atlético.

Dortmund's resolve and ability to come up big in the clutch has come into question in the past. Look no further than the final Matchweek of the 2022-23 campaign. But on Tuesday, at least, Dortmund was made of the right stuff.

Loser: Barca's Composure

It all went wrong for Barcelona, but it didn't start that way.

When Raphinha scored the game's first goal to give Barcelona a two-goal advantage in aggregate, it sure looked like the Catalans were off to the semifinals.

And then, calamity.

Ronald Araújo was sent off on a straight red for denying what was deemed a clear goal-scoring opportunity:

Xavi and goalkeeping coach De La Fuente were also sent off on reds:

João Cancelo fouled Ousmane Dembélé in the box, setting up Kylian Mbappé for a penalty that would give PSG the advantage in aggregate:

And by the time the dust settled, a 10-man Barca conceded four goals and continued what has been an absolute nightmare of a season.

Just another miserable night in Barcelona.

Winner: PSG's Opportunism

Yes, PSG were handed the man advantage in the first half. But they also were trailing by two goals in aggregate at the time and needed a heroic performance to get back into the proceedings.

They offered just that, and then some:

Barcelona will rue the lack of composure, but PSG truly made them pay for every last error. An impressive display of maximizing the opportunities handed to you by the Parisiens.

Loser: Atlético's Normally Stout Defense

Coming into Tuesday, Atlético Madrid had given up four or more goals just twice this season. Diego Simeone's charges were not in the business of having full defensive meltdowns.

That made the collapse against Dortmund all the more surprising.

In a strange evening of football, perhaps it was only fitting that Atlético lost its identity.