The cameras were trained on Harry Redknapp in the stands at Old Trafford, but QPR's new manager was overshadowed by the man who has just been given his own statue at Manchester United.

Sir Alex Ferguson's starting lineup failed, but he knew when to change things. With United trailing to Jamie Mackie's goal and in danger of losing their third straight game to a side without a Premier League victory all season, he went to his bench. 

Javier Hernandez and Anderson replaced Paul Scholes and Ashley Young. Twelve minutes later, United led 3-1, and the subdued home crowd finally had something to shout about.

Once again, United had to come from behind to win—taking their comeback-points tally to 18 this season. Once again, it took them until the second half to find a cure for their mediocrity.

Hi-res-156897613_crop_exact United players trudge back to the halfway line after Mackie's opener for QPR
Laurence Griffiths/Getty Images

Mackie's opener for QPR on 52 minutes was thoroughly deserved. The visitors were bright and full of ideas and looked a team ready to rebound after the sacking of Mark Hughes this week.

Adel Tarrabt was in the mood and seeing plenty of the ball, while Shaun Derry and Alejandro Faurlin—at the fulcrum of Rangers' midfield—were doing a fine job of closing United down as they advanced on goal. 

Such was Rangers' togetherness and defensive efficiency, it was hard to believe we were watching the Premier League's bottom club. 

Hi-res-156897970_crop_exact Substitutes Anderson and Hernandez celebrate United's third
Laurence Griffiths/Getty Images

Equally, such was United's lack of penetration and imagination in the final third, it was hard to believe we were watching a team with a chance to go top.

Then Ferguson made his changes. Anderson added purpose in place of Scholes, who was ineffective at United's hub and—like fellow veteran Ryan Giggs last week against Norwich—did little to justify his starting spot.

And Hernandez, in the grips of a goal binge, replaced Young to give United more focus centrally and ask a different question of the QPR defence.

The complexion of the game changed immediately. United levelled when Jonny Evans reacted quickest to head home from close range, then went ahead with a powerful header from Darren Fletcher—the midfielder's first goal since his lengthy absence from illness.

Hi-res-156897729_crop_exact Jonny Evans heads United level
Laurence Griffiths/Getty Images

QPR's defence was culpable both times—failing to deal with Wayne Rooney corners and paying the price twice within the space of five minutes.

You might argue it was pure coincidence the goals came so quickly after Ferguson made his substitutions, but—as if to make it absolutely clear he'd changed the game—United's third was a substitutes' production from start to finish.

Anderson took possession in midfield and drove at the QPR defence. The Brazilian dipped a shoulder, rode a challenge and played in Hernandez for the Mexican's eighth goal in eight games.

In one clinical passage of way, United's two substitutes produced a lesson in everything their teammates had been missing for the first hour at a rain-soaked Old Trafford:

Anderson was indeed impressive. He added energy and drive to United's midfield and furthered his argument as a starter.

Did Ferguson get his selection wrong against QPR?

Submit Vote vote to see results

Ferguson was widely criticised for starting Giggs against Norwich. His decision to start Scholes against QPR will also be questioned. With the likes of Anderson, Tom Cleverley and Phil Jones waiting in the wings, perhaps it's time he trusted the next generation.

It's nothing new for people to doubt Ferguson's judgement, of course. And those clamouring for the United manager to approach things differently should be reminded his team sit top of the league and are comfortably through to the Champions League knockout stages.

The results can't hide United's flaws, however. Ferguson's midfield is a work-in-progress, while United's defence continues to leak goals too easily. (United have conceded first in nine of 13 Premier League games.)

Thank goodness for their bounce-back ability—because without their collection of comebacks, United would be in mid-table.

This one was all down to Ferguson.