Real parted ways with Alonso a little more than seven months after appointing him, following a poor run of results in all competitions.
The other semi-final will see an Italian side, Milan or Roma, come up against Bayer Leverkusen or West Ham.
Forward Rasmus Hojlund scored twice to allow Manchester United to come back from a goal down and get a 2-1 win at six-times Czech champions Viktoria Plzen in the Europa League on Thursday.
In an early match, Norwegian side Bodo/Glimt secured a 3-2 home victory against FC Porto thanks to a brace from Jens Petter Hauge, despite going down to 10 men in the 51st minute.
While there are suggestions that Ruben Amorim's comments at Sunday's press conference triggered his axing, the verdict was clear given his under-performance in the hot seat.
Atalanta beat Bayer Leverkusen 3-0 in the Europa League final
'Following a meeting this afternoon, the SAG have formally written to the club and UEFA to advise no away fans will be permitted to attend Villa Park for this fixture.'
Summary of the Europa League semi-final matches played on Thursday.
IMAGES from the UEFA Champions League matches played on Tuesday
IMAGES from the Europa League matches played on Thursday
From Royal Challengers Bengaluru's historic first IPL title to star javelin thrower Neeraj Chopra finally breaking the iconic 90-meter mark to India women winning their first cricket World Cup, this was the year of long-awaited victories and record-breaking feats.
'Disorderly conduct, riots, injured police officers, and damage to infrastructure -- this is not a soccer game, this is a breach of order and serious violence.'
Rennes denied late Europa League equaliser due to little-known rule
Lazio, who had won all four previous games, were held to a frustrating scoreless draw by a Bulgarian side who came to defend.
De Ligt's last-gasp equaliser snatches dramatic draw for Man United at Spurs
Liverpool will take on LASK, Union Saint-Gilloise and Toulouse in the Europa League group stage while debutants Brighton & Hove Albion will face Ajax Amsterdam and Olympique de Marseille following the draw on Friday.
IMAGES from the Europa League semifinal matches played on Thursday.
Sevilla maintained their incredible record in the competition after an otherwise difficult season.
Jose Mourinho's side top Group G with a maximum nine points, three clear of second-placed Slavia.
'I did my best on the field and off the field, and by winning the Europa League, I thought I'd done everything I could and achieved.'
'We've crammed in weeks of what you'd normally do into five days, so you know, we have asked a lot, but the first half was a long way short from where we want to be physically.'
Qarabag had chances, Tural Baymarov missing from the penalty spot just before the hour mark and Junior hitting the woodwork, but Spurs stayed in control of the match.
Manchester United's season, already their worst in the Premier League, hit a new low with their 1-0 defeat to Spurs in that final in Bilbao that denied them a spot in this season's Champions League.
Brighton secured their second victory of the competition with a comfortable win at Ajax thanks to goals from Ansu Fati and Simon Adingra.
Arsenal sailed through the Europa League group stages, winning five of their six group matches and take on Sporting next, who overcame Denmark's FC Midtjylland in their playoff.
The first legs of the ties will take place on February 16, with the return match a week later on February 23.
Sevilla will bid for a record-extending seventh Europa League title when they face AS Roma in the final in Budapest on May 31, after Jose Mourinho's side drew 0-0 at Bayer Leverkusen to secure a 1-0 aggregate victory in their semi-final.
PSV fan assaulted Sevilla goalkeeper Marko Dmitrovic, punching him in the face before being wrestled to the ground by the Serbian.
Liverpool shrugged off the absence of Mohamed Salah as midfielder Dominik Szoboszlai scored an 88th-minute penalty to give them a 1-0 Champions League win at Inter Milan.
The teams finished level at 3-3 on aggregate in the tie but the Lisbon club advanced to the quarter-finals after Adan kept out Martinelli's weak effort.
IMAGES from the Europa League matches played on Thursday.
Bruno Fernandes milestone and late drama lift Manchester United past Chelsea with a chaotic 2-1 win over Chelsea at Old Trafford
A round-up of Tuesday's action in the UEFA Champions League.
Mouth-watering matches lined up as PSG to face Bayern and Barcelona in Champions League opening stage.
IMAGES from the Europa League matches played on Thursday.
Action from Europa League matches played on Thursday.
Man United boss Amorim says he has no plans to quit
Images from the Europa League semi-finals first Leg between Athletic Bilbao and Manchester United, Tottenham Hotspur and Bodo/Glimt.
Barcelona were shaken up by Eintracht Frankfurt but took a first step in their bid to reach the Europa League last four as a second-half goal by Ferran Torres salvaged a 1-1 comeback away draw in their quarter-final first leg on Thursday.
Liverpool have signed French striker Hugo Ekitike from Eintracht Frankfurt, the English Premier League side announced on Wednesday.