Rasmus Hojlund was furious with his teammate
"Follow, follow, follow, 'cause United are going to Bilbao," the optimistic Manchester United fans sang. A fourth final in three seasons is still eminently achievable.
There was no win to celebrate against Real Sociedad, grateful for the contentious and overly officious intervention by the Video Assistant Referee from the Netherlands. But even this United side should back themselves to progress past sedate Sociedad.
United may be back in the Basque Country twice, with Athletic a potential semi-final opponent before the final at their San Mames stadium. The 1,943 United supporters in the Reale Arena can be hopeful of another European trip to Lyon or Bucharest in April - and with something riding on the season in the run-in.
United were guilty of more profligacy until one of their most profligate converted. Joshua Zirkzee's goal was casual and as slow as the game and still good enough to deceive the flat-footed goalkeeper Alex Remiro.
Zirkzee lacks the requisite quality but not the character. Four days after his limp penalty gave Fulham victory in the FA Cup shootout, this was a laudable response to that disappointment. United fans serenaded Zirkzee jubilantly this time after his sorrowful send-off on Sunday. It was his second goal in 17 games and sixth for the club.
In their sixth game together in the starting line-up, one of Zirkzee and Rasmus Hojlund scored. Hojlund was more threatening than his recent harmless displays yet he did not have a shot at goal and it is now 19 goalless games.
Zirkzee's sudden strike on 57 minutes meant United would not completely curse their dwindling conversion rate. Even Bruno Fernandes, their most clinical ball-striker, was denied by a brilliant goal-saving block by Aritz Elustondo in the first half. United have now gone 20 successive first halves without a goal from open play.
Spanish sides have ejected United from Europe at the knockout stage on the last six occasions. United will have breathed a sigh of relief that their old scourge Sevilla, responsible for half of those losses, are unable to continue their love affair with the Europa League in this year's edition.
Sociedad, with 23 goals in 26 La Liga matches and a -4 goal difference, will not be daunting visitors at Old Trafford next Thursday. Their goal threat was palpable only after Mikel Oyarzabal's 70th-minute penalty.
You can see why Antony has cut the mustard in La Liga. His agent, Junior Pedroso, had the brass neck to accuse Ruben Amorim of "devaluing" the Spanish top flight. Sociedad, a top-half side, played so slowly they might have been still drowsy from their siesta for the early kick-off.
This did not feel remotely like a European knockout tie, never mind United's most consequential match in 35 years, as billed by some. The build-up for United's return to Spain was miniscule in a week that there was a Madrid derby in the Champions League and ten-man Barcelona prevailed away to Benfica.
The stadium was sprinkled by empty seats, including in the away section. Plenty of spares were available for any ticketless United fans who travelled, blamed on Ineos scrapping the European away ticket collections. 4,000 Sociedad tickets went unsold.
Sociedad's recent crowds have been in the 20,000s and their highest attendances this season were for the visits of Madrid and Barcelona. It has been an age since United could be credibly bracketed with those colossal clubs.
United will have been buoyed by the last-minute withdrawal of Sociedad midfielder Martin Zubimendi, seemingly bound for Liverpool in the summer and now of interest to Arsenal. Amorim urged United to quicken the tempo yet the glacial pace benefited them, in particular Casemiro.
Casemiro had a propitious pre-season when matches would descend into walking football. No Spanish club could afford him but, on this evidence, he would still coast through the league he graced in the white of Madrid for nine years.
Amorim was coincidentally clad in black three days before United supporters have been urged to don the colour to symbolise that the club is "slowly dying". If anyone received a death stare it was Diogo Dalot.
Hojlund gave Dalot a verbal rocket in the 20th minute after the right back failed to cross for the Dane, sprinting towards the near post. Dalot apologetically high-fived Hojlund seconds later during a pause to allow Noussair Mazraoui to break his fast as he continues to observe Ramadan.
Dalot at least learnt from his transgression to pick the right pass with a pull-back for the unattended Fernandes later in the half and tee up Alejandro Garnacho to cross for Zirkzee. Fernandes and Leny Yoro, eschewed the celebrations after Zirkzee struck.
Hojlund was looking at the heavens again in the 56th minute as Patrick Dorgu botched a breakaway with his compatriot and Alejandro Garnacho vacant to his right. He did it again when the blunt Garnacho drove the ball into the side-netting for a second time.
The resigned manner in which Dorgu collapsed to the turf in the first half suggested his race was run. Amorim put his hands on his head and instructed Ayden Heaven, Harry Amass and others to warm up. Dorgu soldiered on and the night did not take a turn for the worse.
And United could be going to Bilbao.