With the first leg of this tie ending all even the Camp Nou, a victory for both sides will be essential order to advance further in this competition.
Due to the recent removal of the away goals rule in all UEFA competitions, the winner of this match will advance to the next round of the Europa League no matter the scoreline. If the score remains even at 90 minutes, 30 minutes extra time will be added on, followed by a penalty shootout if necessary.
Manchester United and Barcelona have produced many historic match ups in the past such as the 2009 Champions League Final, and we expect no exceptions in tonight's fixture.
Erik Ten Hag has lead Manchester United to new heights since taking over, but this is arguably the most important game in his reign at Old Trafford so far. The Red Devils are currently unbeaten in 8 games across all competitions, so confidence levels will be high heading into tonight's fixture.
However according to form, there are very few sides that compete with Barcelona. Xavi and his men have not lost a competitive game since October, as they are currently flying high at the top of the La Liga table.
It is not often that you will find a match as hard to predict as this, however Manchester United may be the slight favourites playing in front of a home crowd.
● Team News
Erik Ten Hag's squad is almost entirely fit, besides Donny Van De Beek and Christian Eriksen. Both players players are currently out of action due to long term injuries.
Anthony Martial is believed to be back in training but it is highly unlikely that he will start, hence Wout Weghorst is expected to lead the Manchester United attack.
Diogo Dalot has looked slightly shaky since his return from injury, so Erik Ten Hag could prefer Aaron Wan-Bissaka the right back slot.
Marcel Sabitzer and Lisandro Martinez are both eligible to play the second leg, as they missed the first leg due to suspension.
Xavi will be forced to make two changes from the team that started in the first leg, as Gavi is suspended for this fixture and Pedri is sidelined due to injury.
The replacements for the two young Spaniards are expected to be Franck Kessie and Ansu Fati, who will play in their preferred central-midfield and left-wing positions respectively.
Other than the changes mentioned above, Xavi will likely make no further changes to the lineup from the first leg.
● Predicted Lineups
Manchester United: De Gea, Shaw, Martinez, Varane, Wan-Bissaka, Casemiro, Sabitzer, Fernandes, Rashford, Weghorst, Sancho
Barcelona: Ter Stegan, Alba, Alonso, Araujo, Kounde, Busquets, Kessie, De Jong, Fati, Lewandowski, Raphinha
● Key Players
Manchester United- Marcus Rashford
Since his return from the World Cup in December, Rashford has turned into a different beast, and in this period of time he has arguably been the best footballer on the planet.
His ability to destroy opposition defenders combined with his clinical finishing in front of goal has caused nightmares for his opponents.
His numbers have been nothing short of spectacular this season, with 14 goals and 3 assists in his 24 Premier League appearances.
As proven in the first leg, Marcus Rashford is the focal point of the Manchester United attack and he has shown no signs of slowing down this fantastic form.
Barcelona- Raphinha
Maybe a less obvious choice than Rashford, but one that is quite justified is Brazilian winger Raphinha.
Raphinha hasn't exactly set the world alight since his arrival from Leeds last summer, but at times he has shown exactly why Xavi brought him in.
Raphinha is quick, skillful and has a deadly left foot, but can also create chances for his teammates.
The 26 year old was arguably Barcelona best player on the pitch in the first leg before being substituted off in the 83rd minute, so Xavi will be hoping that Raphinha can keep the momentum going and turn up at Old Trafford.
● Match Details
Where is the game being played?
The game will take place at Old Trafford stadium in Manchester.
What time is kick-off?
The game will kick off at 20:00 GMT on Thursday evening.
How can I watch?
The match will be live on BT Sport 2.