The La Liga leaders over powered Ole Gunnar Solskjaer’s side, with Messi scoring two goals inside the first 20 minutes to put the tie beyond the Premier League side and Messi was full of praise at full time.
“We put in a spectacular performance, but that is what we can do.
“We did not perform well in the first five minutes, before after that we dominated.”
Barcelona did endure a few scares from United, and Messi acknowledged that any slip ups will be punished in the semi finals.
“We cannot start a Champions League game like that.
“A bad five or ten minutes can make things very difficult, and possibly mean being knocked out. We must be aware of that.”
Barcelona return to La Liga action this weekend as they host Real Sociedad, and despite already having a nine point lead at the top, Messi stated that the team will not be getting ahead of themselves.
“We have gone one step further tonight, but we must be patient.
“Next we must focus on the league and winning the title, and then concentrate on the Champions League semi finals.”
Ernesto Valverde’s side will face either last season’s finalists Liverpool or Porto.