Remarkably, this was the first meeting between these European giants since 1965, but, needing a win to have any chance of progression, Benfica had no time for sentiment. Instead, they created the first chance when a seventh-minute corner caused chaos in the Real box before ricocheting off Tomas Araujo and going narrowly wide.
Los Blancos received another let-off soon after, when Davide Massa awarded the hosts a penalty for a foul by Jude Bellingham on Gianluca Prestianni, only to reverse his decision after consulting the pitchside monitor.
Prestianni’s luck was still out midway through the first half, when his curling effort was tipped onto the crossbar by Thibaut Courtois.
Then, the resulting corner was recycled by Nicolas Otamendi, but Fredrik Aursnes’ volley lacked the conviction to beat the goalkeeper.
A 30-yard rocket from Arda Guler sailing a whisker wide was a warning sign that the one-way traffic was over, and so it proved after 30 minutes when Kylian Mbappe arrived at the back post to head home a Raul Asencio cross to become the first goalscorer in this H2H since Ferenc Puskas.
However, the lead lasted just seven minutes; Asencio was denied a headed goal of his own by Anatoliy Trubin, and Benfica’s next attack saw Vangelis Pavlidis shrug off the Real defence before crossing for Andreas Schjelderup, who put his header out of Courtois’ reach.
Alvaro Arbeloa’s side were hanging on before the interval, as a Schjelderup shot was blocked on the line by Federico Valverde prior to Leandro Barreiro nodding wide from three yards. Ultimately, the record UCL champions fell behind in added time, when Aurélien Tchouameni hauled Otamendi down in the area, with Pavlidis powering his subsequent penalty down the middle.
Having survived a golden chance for Vinícius Junior in the opening exchanges of the second half, As Águias’ night got better when a flowing move from deep in their own territory resulted in Schjelderup cutting in from the left and beating Courtois at his near post.
But just four minutes after the Norwegian completed his brace, Mbappé did the same with a neat finish into the bottom corner after excellent play from Guler to set him up.
Trubin was kept busy by Guler and Bellingham as the half wore on, before Barreiro was thwarted by Courtois and key blocks denied both Mbappe and Schjelderup hat-tricks.
A poor night got worse for Los Merengues in added time when they were reduced to nine men, as Asencio was shown a second yellow card and Rodrygo joined him by receiving two yellows in 60 seconds.
Then, in the final minute of added time, the hosts threw everyone forward for an Aursnes free-kick, and goalkeeper Trubin rose highest to score in the most dramatic fashion to send Benfica into 24th place with the last action of the game.
While Mourinho may be towards the end of his career in management, he often remains involved in the most memorable of moments.
Flashscore Man of the Match: Andreas Schjelderup (Benfica)