Coutinho provided the knockout blow to the Red Devils in the quarter-final second leg. His wonderful finish from outside the box just after the hour made it 3-0 on the night, and 4-0 on aggregate, following Lionel Messi's first-half double:
The Brazilian, who has been in and out of the Barca first team and faced criticism ever since he moved to the Camp Nou from Liverpool, celebrated by putting his fingers in his ears:
It was a provocative move, but Lenglet said it was not an issue, per Tom Webber of Goal:
"I do not care about the celebration, what matters to me is the goal. Coutinho is a great player, he has balls."
Busquets, meanwhile, hailed Coutinho's quality: "I did not see anything. I know he celebrated with anger, with desire. It was an important goal for him after the criticism he has received. He is a world-class player."
Barca will find out their semi-final opponents on Wednesday as they will face the winners of Liverpool's tie with Porto:
The Reds hold a 2-0 lead from the first leg that they now need to protect when they visit the Estadio Do Dragao.
Remarkably, their appearance in the semi-finals this season will be their first since they last won the tournament in 2014-15.
That season, Barca boasted the remarkable front line of Luis Suarez, Neymar and Messi, who swept all before them on their way to a treble.
The same prize potentially awaits the Blaugrana this term, as they have La Liga all but wrapped up and face Valencia in the Copa del Rey final on May 24.