Unheralded Sporting Braga edged domestic rivals Benfica 1-0 in a nerve-jangling semi final second leg on Thursday to set up an all-Portuguese Europa League final with league champions FC Porto.
Braga's success saw the club from northern Portugal advance on away goals after a 2-2 aggregate draw and thwarted neutrals' hopes of a clash between traditional rivals Porto and Benfica in the final in Dublin on May 18.
Domingos Paciencia's side, runners-up to Benfica in last season's Portuguese championship, will be appearing in their first ever European final.
In stark contrast, two-time European champions Porto are bidding to complete a treble, having already sewn up the Portuguese league title and reached the final of the Portuguese Cup on May 22.
Captain Vandinho's goal in the away leg meant Braga went into the game at their Estadio Municipal home needing just one goal to turn the tie around and it duly arrived in the 19th minute.
Static defending allowed Custodio to launch a running jump at Hugo Viana's outswinging left-wing corner and his bullet header put the hosts ahead on away goals.
Right-back Silvio came close to a second goal for Braga on the half hour, but his low shot from the edge of the box flashed inches wide of the far post.
Benfica did not threaten until three minutes before the break, as Javier Saviola swept a shot against the right-hand upright from Oscar Cardozo's low centre before Fabio Coentrao slammed the rebound over the bar.
Benfica's best chance of the night also fell to Saviola, but he was unable to convert from inches with 10 minutes remaining after Luisao flicked on a corner at the near post.
There was even more drama to come in the 88th minute, when substitute Alan Kardec's back-post header beat Braga goalkeeper Artur only for Paulao to hack the ball off the line.
"I'm no hero," said Custodio. "We all are heroes. Those who played, those who stayed on the bench, those who stayed in the stands, the fans. We will play to win the final, it's our ambition. We are true warriors."
Colombian striker Radamel Falcao entered the history books as Porto, who are yet to lose a league game this season, completed an emphatic 7-4 aggregate victory over Villarreal despite a 3-2 loss at El Madrigal.
Falcao claimed his 16th goal in this season's tournament, breaking Jurgen Klinsmann's 15-year record for the most European goals in a single season.
Villarreal went into the game trailing 5-1 from the first leg but took a 17th-minute lead when Cani side-footed home following a one-two with Marco Ruben.
Porto equalised five minutes before half-time via a deflected effort from Brazilian forward Hulk, however, and in the 50th minute Falcao claimed his record-breaking goal to put the tie beyond the Spaniards.
Victory would have made Andre Villas Boas's team the first in history to win eight consecutive away games in European competition, but Joan Capdevila drew the hosts level before Giuseppe Rossi netted from the penalty spot in the 80th minute.