United were victorious in a superb 4-0 display.
Story of the game
The game in Turin took no time to get the blood flowing, with both sides having chances within two minutes of the opening.
Rashford received a long pass after he shrugged off the Sociedad defender but then could not guide his shot past the goalkeeper. Then former Red, Adnan Januzaj, was inches away from finding the top left corner with a curling effort.
Against Sociedad's high defensive line, United looked dangerous and Rashford should have opened the scoring after Fernandes made a run in behind and played a pass across goal. The English forward had only the keeper to beat, but his shot was saved again.
While he did not seem to have his shooting boots on, Rashford was able to show some of the creativity that he has developed in the last year to turn provider for Fernandes.
The Portuguese's run was expertly found by United's number 10 and Fernandes managed to slot the ball into the back of the net for his 20th goal of the season after the Sociedad's defenders were unable to deal with the danger.
It was not all plain-sailing for the Reds though as Sociedad grew into the game and finished the first half well.
Imanol Alguacil's side came close to an equaliser after Eric Bailly needed to acrobatically clear the ball off the goal line following a headed effort, yet it was deemed that the Sociedad forward headed the ball out of Dean Henderson's gloves.
It was not long after the start of the second half when Ole Gunnar Solskjaer's side doubled their lead with another deadly counter-attack. Rashford played a ball into James and he touched the ball into Fernandes' path, who was clinical to find his and United's second of the match.
Rashford was then able to give United a comfortable 3-0 lead with a calm finish into the bottom corner after a wonderful through-ball from Fred.
With Sociedad continuing with their high-line, the chances continued for United. James found the back of the net after he received a cross from Mason Greenwood although it was brought back for an offside.
The game ended with dominance from the Reds, who introduced 18-year-old Amad for his debut in the 83rd minute.
The killer blow for Sociedad was made in the 90th minute, as James ran 40 yards to put United's fourth past Álex Remiro in the Sociedad net and secure the 4-0 win for the Reds to go into the second leg next week.
Fernandes reaches goalscoring milestone for the season
With his two goals, Fernandes was able to surpass 20 goals for the season and it highlights his importance for United.
Many questioned whether the former-Sporting man could carry on his incredible output from the back-end of last season into this campaign and it seems that his 33 goals and 19 assists in just 58 appearances have firmly answered those questions.
Fernandes is critical to everything United do and while that might not be great when he is not in the lineup, like in the dull 1-0 FA Cup win against West Ham, you can only admire how he manages to turn up and convert the majority of the time for this United team.