Sir Alex Ferguson hailed Cristiano Ronaldo's winner against Lyon as his most important goal of the 30 he has already struck this season.
The winger finished well after a scrappy build-up as United triumphed 1-0 on Tuesday and 2-1 overall to secure a place in the quarter-final draw of the Champions League.
Ferguson said: "His goal tonight was well-taken. It may not be the best goal he has scored this season but it may turn out to be one of the most important.
"He has scored 30 goals already this season, and it is only the start of March. Potentially there are 16 or 17 games ahead of him, so he could end up with an even higher score.
"For a wide player to do that is fantastic. It is a great contribution."
United should have ended up more comfortable winners but were guilty of over-elaborating and not making the most of their opportunities.
Ferguson admitted as much, adding: "We should have done more with the possession and the chances we had.
"Some nervousness came in, because we didn't take the chances and kill the game - so we were on a knife edge.
"The more important part of it was that we were defending well. The back four were quick to advance on to their opponents, and that made a big difference.
"Apart from the shot from (Kader) Keita that hit the post, they didn't really make a chance."
United's win and Arsenal's victory in Milan means that all four English sides could make it into the quarter-finals if Liverpool and Chelsea come through their ties.
Ferguson has no issue with playing another Premier League side or not in the next round.
He said: "I expect Chelsea to get through - and if Liverpool do too it's a 40% chance of getting an English team.
"I don't think it matters who you play - they are all difficult games.
"That's why the quarter-finals throw up good teams, and the important thing is to be there ourselves."
The victory completed a record-equalling 10th consecutive home win in the Champions League for United.
"It equals Juventus' record," Ferguson noted.
"The supporters have a lot to do with it - and they were fantastic again tonight."
Lyon coach Alain Perrin had no complaints about the result over the two legs - but said the decisive moment was Carlos Tevez' late equaliser in the first leg.
Perrin said: "You cannot argue with the fact that Manchester United deserved to go through over the two legs, even if our effort perhaps deserved more than we got.
"I think the late goal in the first leg influenced this match, and we have one or two regrets from this game.
"We tried to get out of our half more often, but United's pressing game was a great danger for us and made it very difficult.
"Now our players have to turn the page, forget about this and concentrate on the league and the French Cup."
