The La Liga side overcame Strasbourg in Thursday's other semi-final, meaning the 2026 UEFA Conference League Final will be a meeting between England and Spain in Germany.
Here's a quickfire guide on Vallecano's European pedigree....
History in Europe
Like Palace, the meeting in Leipzig will be Rayo Vallecano's first European final.
But this season isn't their first when it comes to competing across the continent. A beneficiary of UEFA's Fair Play award saw Vallecano participate the 1999/2000 UEFA Cup, via the backdoor of the qualifying rounds.
But after getting themselves into the main draw, they went on an excellent run, reaching the last eight.
Ultimately the Madrid-based club came unstuck in the quarter-final, losing 4-2 on aggregate to fellow Spanish side Alaves.
Coincidentally, Alaves went on to reach the UEFA Cup Final, losing a nine-goal thriller to Liverpool 5-4 – another England v Spain club final that was played in Germany.
