If United continue advancing in the competition they will obtain that important spot in the Champions League next season.
Another United forward whose future is the subject of speculation is Zlatan Ibrahimovic, with the former Paris Saint-Germain star yet to sign an extension to the one-year contract that expires at the end of the season.
But his pinpoint pass in the build-up to Henrikh Mkhitaryan's opener was worth its weight in goals. But somehow Ibrahimovic hit the ball straight at Anderlecht goalkeeper Ruben Martinez.
Ibrahimovic is yet to reveal if his initial one-year United contract will be extended in the summer.
The 24-year-old has proved himself a top-flight talent and earned his first England call-up this season.
Additionally, Arsenal and Tottenham are two competitors left for United to face, and they are not the easiest of teams to compete against. Sunday was the template for what Man Utd need for big games.
"We have been together for nearly 10 months. We've played 11 matches already, so let's see if we can go to the final". He is fit and is on the bench.
"We do need a goal tomorrow but we need to be prudent as well".
The United midfielders that got the nod ahead of Herrera were all caught napping when Sofiane Hanni fired in the equaliser.
Rooney, 31, was also absent from the Chelsea game, with an ankle injury that adds to a list of problems that has featured knee and muscular woes and illness since he became United's record goalscorer in mid-January. The Swedish striker looked in pain and held his head in his hands.
The self-proclaimed lion roared in pain but managed to hobble off without the help of the stretcher that was sent on to haul him off the pitch.
Indeed, he has only made nine starts in the Premier League this term - and has started just once in the top flight in 2017.
But from less than six yards out the world's most expensive player somehow managed to scoop his effort over the bar.
Even his mere presence limits chances that would have been available to young talent - for example, whenever he plays, Marcus Rashford and Anthony Martial, two of Europe's most exciting talents, are restricted to the wings or the bench.
Manchester United captain Michael Carrick has confessed that he thought it was going "to be one of those nights" against Anderlecht, only for his side to dig deep for an extra-time win. We lost players in the January market and didn't buy players.
Anderlecht put on an impressive show here, as did their vocal travelling support - something acknowledged by Mourinho after the final whistle as he went over to applaud them.