Aston Villa’s first major European semi-final since 1982 fell flat and unless they can inspire a ­memorable turnaround in the port of Piraeus next Thursday, their adventure will end in disappointment.

A few minutes after the final whistle, Evangelos Marinakis, the Olympiakos and Nottingham Forest owner, was basking in victory, high-fiving supporters in an understandably boisterous away end. Any officiating concerns were on the back-burner here.

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Olympiakos stormed into a two-goal lead and despite Ollie Watkins pulling a goal back before half-time and Moussa Diaby restoring parity after the break, the Greek side roused again to run out 4-2 winners, Ayoub El Kaabi helping himself to a hat-trick.

The Villa captain, John McGinn, made no attempt to dress it up. ­“Everything that could have gone wrong did,” he said.

Perhaps Villa will take heart from the way the Greek side surrendered a three-goal lead against Fenerbahce in the quarter-finals, before prevailing on penalties, or the manner in which they crashed 4-1 at home to Maccabi Tel Aviv in the last 16, before winning 6-1 in the return leg. “We need to play a lot better than we did tonight but we’re more than capable of doing it,” McGinn said.

A frustrating night was typified by Douglas Luiz’s penalty miss on 84 minutes, the midfielder dragging his shirt over his face after ­squandering an opportunity to reduce the deficit. Douglas Luiz raised the palms of his hands to supporters by way of apology before leaving the field.

Fiorentina will take a narrow lead into their second leg with Club Brugge after a thrilling Europa Conference League semi-final, first leg in Italy. La Viola led after just five minutes through Ricardo Sottil's fine finish but Hans Vanaken levelled from the penalty spot 12 minutes late after a harsh handball decision against Cristiano Biraghi.

Andrea Belotti put the hosts back in front before half-time, finishing neatly after Giacomo Bonaventura's powerful shot was spilled by keeper Nordin Jackers. The visitors went down to 10 men on the hour mark when Raphael Onyedika received two bookings in three minutes, but Thiago struck straight away to level again.

M'Bala Nzola [pictured], on as a late substitute, grabbed the winner in stoppage time as he clinically found the bottom corner. Fiorentina emerge as slight favourites to reach their second straight Conference League semi-final, but there is still plenty to play for back in Bruges next Thursday. Guardian sport

On a dispiriting night, the only real positive for Unai Emery occurred 125 miles away, with Tottenham’s defeat at Chelsea meaning Villa can seal a Champions League berth as early as Sunday. If Tottenham lose at ­Liverpool and Villa win at Brighton, Villa will play in Europe’s premier competition for the first time since  1983.

For now, though, the focus is on overturning this defeat to lift silverware this season. As the last English team standing in a European competition, Villa were flying the flag on behalf of the Premier League.

They did not do themselves justice, ­trailing 2-0 inside 29 minutes, El Kaabi ­scoring both goals, the first of which was awarded after a VAR review showed Matty Cash played the striker onside. El Kaabi netted after latching on to Chiquinho’s cute flick, Villa’s high line not quite high enough. His second goal came from a clever pass by the former Wolves winger Daniel Podence.

A break in play on the half-hour, owing to an injury to Francisco Ortega, allowed Emery to give his players a piece of his mind. He went ballistic at Douglas Luiz, gesticulating with fury. Then it was Clément ­Lenglet’s turn to face the music and then Robin Olsen’s. Olsen, the ­experienced Sweden goalkeeper, began in place of the suspended Emiliano Martínez. All the while the burly frame of Marinakis stood at the door of an executive box in the Trinity Road Stand.

Villa were in a state of shock but stirred before the interval. Leon ­Bailey appeared to be felled by Ortega in the box, only for the Italian referee, Marco Guida, to wave away appeals for a penalty. A minute later, Watkins halved the deficit with a clinical, first-time finish.

The move began with Olsen, Ezri  Konsa pushed a pass into Cash, who found Diaby, who slipped in Watkins.

The second half was delayed because of a medical emergency in the Holte End. The lights of the ambulance that transported a supporter were still flashing as the game restarted about five minutes late. Villa began the second half quickly, as they did the first, but this time they had something to show for it with Diaby sneaking a shot in at Kostas Tzolakis’s near post from an acute angle. Bailey picked up Lenglet’s diagonal pass and freed Diaby to do the rest.

Emery offered his approval, a hearty double thumbs up on the sidelines. The same could not be said three minutes later, when the referee awarded a penalty against Douglas Luiz, penalising the midfielder for handball at a corner. El Kaabi sent Olsen the wrong way from 12 yards.

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“We respected our rival but we were not scared of Aston Villa,” said the Olympiakos head coach, José Luis Mendilibar, who in February became the club’s third manager of the season.

Villa felt aggrieved but more pain followed, Olympiakos restoring their two-goal advantage in ­freakish ­fashion. Santiago Hezze took aim from 25 yards and his strike clattered the back of Konsa and wrongfooted Olsen. The keeper shifted his feet to the left as Hezze let fly and though he managed to get his right arm on the ball he was powerless to stop the ball going in.

Douglas Luiz missed the chance to limit the damage after David Carmo was penalised for a foul on the ­substitute Jhon Duran. After a considerable wait to take his spot-kick with some tangling on the edge of the area, the Villa midfielder fluffed his lines.

Olympiakos have been hit-and-miss at home and now Villa must mount a memorable comeback on the outskirts of Athens to reach the final. “We have a mountain to climb but we know we’re capable,” McGinn said.