United looked set to take a 1-0 lead into next week's second leg but Leander Dendoncker's thumping header four minutes from time gave the Belgian's an important equaliser.
The away side had ample opportunities to kill the game with goalscorer Henrikh Mkhitaryan and Paul Pogba guilty of misses.
Manchester United player ratings against Anderlecht Thu, April 13, 2017
Express Sport rates the Manchester United players' performances during their 1-1 draw with Anderlecht
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Which Manchester United players impressed during their 1-1 draw with Anderlecht?
Jose Mourinho was not happy to draw the game
And Mourinho has pinned the blame for United's draw on the shoulders of his forwards.
He said: "If I was a Man United defender I would be very upset with the attacking players because they had to kill the game and they didn't."
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