The Red Devils won 4-0 on the night, with a Wayne Rooney hat-trick – his first goals since April – and Ander Herrera’s strike making it a comfortable evening in Belgium.
United could even afford the luxury of Javier Hernandez missing a penalty towards the final minutes.
Also through are Bayer Leverkusen, who overcame a 1-0 first leg deficit to beat Napoli 3-1 on aggregate.
Hakan Calhanoglu, Admir Mehmedi and Karim Bellarabi got the goals for the German side, with Napoli also having Mauricio sent off for a second yellow midway through the second half.
Out of the competition go Portuguese giants Sporting Lisbon, who lost 3-1 on the night to CSKA Moscow for a 4-2 aggregate defeat.
Sporting had looked on their way for a comfortable win after Teofilo Gutierrez scored, but Seydou Doumbia’s brace, coupled with a late Ahmed Musa strike, turned the tie on it’s head.
Also through are Belarusian side FC Bate on the away-goals rule against Partizan Belgrade, and Kazakhstan outfit FK Astana, who beat Apoel 2-1 on aggregate.