Ainsworth received a well-deserved pat on the back from Ferguson and the caretaker manager said: "We only had a chance to have a couple of words.
"He told me 'well done' and 'good luck' at the end but that's more than I've had in 20 years of football from Sir Alex ,so I'm just pleased to have got that."
The praise from Ferguson did not stop there, with the Scot acknowledging that QPR, who had kept four clean sheets in five matches before Old Trafford, were always going to make life difficult for his side.
"We are used to teams coming here and being hard to break down now," Ferguson said. "It was just a matter of opening them up and taking the first chance but that was difficult.
"QPR haven't lost a lot of goals recently, so it was always going to be difficult. There was some relief when we finally made the breakthrough."
The sum total of the Championship side's first-half attacks were two free-kicks from deep that were over-hit by Martin Rowlands and Ramage as United camped themselves in the opposition half.
Yet Czech goalkeeper Radek Cerny's work was rarely extended beyond routine saves in the first half as United grew more and more frustrated.
The pattern continued after the restart, with a Rangers player always on hand to make a key block and some more wayward long-range shooting from Nani and Anderson.
Park hit a post but finally the breakthrough came when Nani slipped a pass through for the substitute Welbeck, who was clipped by Ramage as he closed on goal.
There was no argument and Tevez produced a confident finish for his first United goal since scoring in the 2-1 win over Liverpool in mid-September.
However, that was the start of some belated pressure from Ainsworth's side and substitute Samuel Di Carmine had the ball in the net with seven minutes left only to be correctly ruled out for offside.
Argentinian midfielder Ledesma could even have pinched an equaliser in the fourth minute of added time but the on-loan Genoa man shot wide after Patrick Agyemang's breakaway.
"It's been a long time since we've come to these places," Ainsworth said. "We're ambitious and we want to be back here on a regular basis and that means Premier League status.
"Teams have to respect us now and believe that one day we'll be back in the Premier League."
That may still seem like a long way off but commitment like this might just take them there.