Alemao's efforts sent the Madrid club to a first European final in their 102-year history.
The 25-year-old became the first player to score in a European semi-final for Rayo Vallecano when he headed home from Andrei Rațiu's inswinging corner in the first leg at Estadio de Vallecas on April 30.
In Thursday's second leg at Stade de la Meinau in Strasbourg, he reacted quickest inside the six-yard box to convert the rebound after Strasbourg goalkeeper Mike Penders pushed out defender Florian Lejeune's cushioned volley, giving Rayo a 1-0 lead on the night and 2-0 on aggregate. Goalkeeper Augusto Batalla saved a 94th-minute penalty from Paraguayan forward Julio Enciso to seal the win.
Afterwards, Alemão pointed upwards as he celebrated and later explained where his thoughts went in that moment.
"I dedicate this goal to God and to my family — to my wife and my children."
Rayo president Raúl Martín Presa had been bullish when Alemão signed for €5.5million in the final days of last summer's transfer window, predicting the striker could earn a call-up for Brazil's World Cup squad under Carlo Ancelotti.
"He is a good signing. If he performs as we expect, he will have the opportunity to wear the Brazil shirt at the next World Cup. That is a personal opinion — we believe he has those qualities. Perhaps he is not so well known because he is not at Manchester City or Arsenal, but he has that potential."
Those words look prescient. Alemão missed the entire month of December with a pubic injury but returned to score twice in a 3-0 win against Turkish side Samsunspor in March, a game head coach Íñigo Pérez described as a turning point.
"The injury had given him trouble. He had not been fully fit but today he responded. You can imagine these scenarios — he deserved it."
Since that match he has added three more goals in 598 minutes, all of them in high-stakes moments. Rayo face Crystal Palace in the Conference League final in Leipzig on May 27.
Alemão arrived as an obscure Brazilian with Polish and Italian roots. He leaves the semi-final stage as the man who put a working-class Madrid neighbourhood on European football's biggest stage.