Manchester United were rampant in hammering Roma 6-2 but Arsenal suffered a 2-1 defeat at Unai Emery's Villarreal in the other Europa League semi-final.
Bruno Fernandes and Edison Cavani scored a brace each as Manchester United came from behind with five second-half goals to thrash Roma 6-2 in the Europa League semi-finals on Thursday.
Fernandes opened the scoring for United in the ninth minute but Lorenzo Pellegrino levelled with a penalty before Edin Dzeko put Roma ahead in the 34th.
Cavani, however, struck in the 48th and 64th minutes to tilt the tie United's way before a Fernandes penalty in the 71st added to their advantage.
Further strikes from Paul Pogba in the 75th and substitute Mason Greenwood in the 86th ensured a big win for United.
The result leaves the 2017 champions United well-placed for next Thursday's second leg in Roma and a place in the May 26 final in Gdansk.
"The result is positive but it's not finished. We are going to have to stay focused and play the second leg with the same mentality," Pogba told BT Sport.
The other English side, 2019 runners-up Arsenal, lost 2-1 at Spain's Villarreal in a game both sides ended with 10 men.
Roma lost midfielder Jordan Veretout, first choice goalkeeper Pau Lopez and Leonardo Spinazzola in the first half but still managed to battle back from a ninth-minute deficit when Fernandes chipped over Lopez after being set up superbly by the 34-year-old Cavani.
Pellegrino netted from the spot into the left corner after a sliding Pogba had handled an attempted cross from Rick Karsdorp.
Roma were 2-1 up in the 33rd when Dzeko tapped home Pellegrino's cross to complete a move which involved a superb defence-splitting pass from former United player Henrikh Mkhitaryan to Pellegrino.
It was Dzeko's fifth goal at Old Trafford after two braces in the past while at Manchester City.
Three minutes after the restart Cavani fired the equaliser into the top right corner off Fernandez and then tapped home in the 64th to put United ahead again.
Fernandes completed his brace from the penalty spot after former United player Chris Smalling brought down Cavani.
Four minutes later Pogba headed the fifth off Fernandes' cross, and substitute Greenwood fired into the far left corner as United ensured a big win against Roma.
Villarreal meanwhile had a dream start against Arsenal when Manu Trugeuros fired into the bottom left corner with the first attempt five minutes into the game.
The Gunners were harmless and went 2-0 down from captain Raul Albiol after a corner was flicked on to him.
Arsenal had Dani Ceballos was sent off for a second bookable offence in the 57th before Nicolas Pepe gave them hope with a 73rd-minute penalty, and Villarreal then had Etienne Capoue dismissed over a second yellow card.
"I'm happy in the second half we picked ourselves and have given us a chance at the Emirates. We showed we are better than them, even with 10 men, so it is up to us. When we play properly we can beat anyone," Arsenal's Bukayo Saka insisted.