Wayne Rooney joined Bobby Charlton as Manchester United's joint-record goalscorer on 249 goals as the Red Devils cruised past former United defender Jaap Stam's Reading and into the FA Cup fourth round.
The Red Devils' captain took just seven minutes to fire the game's opening goal and equal Charlton's record in 215 less appearances, before Anthony Martial added a second in the 15th minute as United threatened to run away with it.
The competition's current holders dominated the rest of the first-half against their Championship opponents but had to wait until the 75th minute to finally make sure of their progression to the next round through Marcus Rashford.
And the striker added United's fourth of the afternoon just four minutes later after a horrific error from Reading goalkeeper Ali Al-Habsi summed up a disappointing return for Reading boss Stam.
Rooney and United could even have added further gloss, but had to settle for four as the joint-record winners of the FA Cup - having done so 12 times - go looking to defend the trophy for the first time this year.
The win also means United have won eight consecutive games in all competitions for the first time since September 2009.
Mourinho rings the changes for United
As promised, Jose Mourinho handed starts to captain Rooney and goalkeeper Sergio Romero. Only Marcos Rojo and Michael Carrick kept their places as the Portuguese boss made nine changes from the away win at West Ham United earlier in the week.
Elsewhere, Ashley Young came in for his 150th United appearance at right-back while attacking midfielder Juan Mata was given an opportunity to continue his goalscoring run, after netting in three consecutive FA Cup appearances.
Out-of-favour winger Memphis Depay and holding midfielder Morgan Schneiderlin were missing from the match-day squad altogether, with the latter recently subject to heavy interest from Everton, while Luke Shaw missed out again through injury.
Stam, meanwhile, named a more familiar starting eleven for promotion hopefuls Reading, making just two changes from their last-gasp away win at Bristol City on Monday.
Former United defender Paul McShane was forced to miss out with a hand injury, meaning Liam Kelly returned, although ex-Red Devils defender Tyler Blackett kept his place.
The only other change saw midfielder George Evans, formerly of Manchester City's Academy, come in for John Swift - who dropped to the bench.
Rooney puts Red Devils ahead early on with historic record-equalling goal
In an exclusive interview with FourFourTwo this week, Stam said that - regardless of his past playing career as a defender - he wants his Reading team to play football the "Dutch way" and to dominate and win games while playing an attractive brand of football.
The Dutchman, who spent three successful years at United between 1998 and 2001 and became a firm fans' favourite, also preached in his pre-match press conference that while the Royals' style on his Old Trafford return would remain unwavering, that they had to understand when and when not to take risks.
And United's quick start showcased exactly why Stam was right to be cautious of their threat, Rashford curling just wide before Rooney brought a save from Ali Al-Habsi inside just three minutes.
But it took just seven minutes for the Red Devils to take the lead and it came through a likely source. Martial did excellently to beat his man before pulling back to Mata, and Rooney got enough on the Spaniard's clipped ball to find the bottom corner for a historic goal.
That, in front of the watching Bobby Charlton, brought the 31-year-old level on terms with the United legend and set the tone for the early stages as the home side dominated proceedings and maintained a constant pressure on Reading.
Before long, United doubled their lead as Martial applied a classy finish for his fourth FA Cup goal in his last seven outings in the competition, having also laid on four assists in that time.
The Frenchman exchanged a one-two Rooney on the edge of the box, latching on to the return before curling through the legs of Liam Moore and into the far bottom corner to put the tie well in United's favour.
The feel-good factor was disrupted somewhat on 19 minutes when Rojo was forced off with a muscle injury that meant Phil Jones had to replace him.
And Reading threatened to compound that disappointment as they briefly grew into the game, Carrick doing well to clear a threatening cross from Roy Beerens in search of Liam Kelly in the centre of the six-yard box.
Chances come and go as United look to extend their lead after Martial's classy finish
Minutes later, ex-Leicester City defender Moore was only inches away from surely finding the bottom corner - although he failed to get any sort of connection on Beeren's volleyed cross across goal at a corner.
Yet Reading's respite was only brief and United soon had more chances to add to their advantage. Al-Habsi required a second attempt to gather Martial's attempt before drawing a sigh of relief at the sight of Rashford firing into the side-netting from an angle after the teenager had beaten the offside trap and rounded the 'keeper.
Al-Habsi, who only signed a new contract with Reading earlier in the week, was face-to-face with Rashford again after Rooney's ball, but came out better on this occasion as he closed down the space to block the striker's attempt.
The home side continued to put together some lovely attacking moves prior to half-time, although Mata - curling high over the bar - and Martial - firing Rashford's low cross wide of the near post - both failed to find a decisive third goal.
In response to the first-half, Stam replaced Blackett with midfielder Jordan Obita at the break as he looked for his side to add to the glimpses of threat they showed.
United took no time at all to settle back into their stride but were fortunate to remain with 11 men after Young caught substitute Obita with a late studs-up challenge that only saw him shown yellow.
Within minutes, they should have added a third, but Rooney fired straight into Al-Habsi from a couple of yards out before Joey van den Berg managed a crucial touch on Rooney's cross to prevent Rashford from tapping in a third.
Quick-fire Rashford double 15 minutes from time puts game beyond any doubt
Reading enjoyed a spell on top, but failed to force Romero into a single meaningful save and United finally scored their long-awaited third through the bright Rashford, who ran on to Carrick's perfectly-timed through ball and slotted past Al-Habsi for his fourth of the goal.
And four minutes later, after the once-exiled Bastian Schweinsteiger's introduction was met with a raucous standing ovation, Rashford added his second and United's fourth thanks to Al-Habsi's mistake - the 17th goal he has conceded in only five games against United.
The goalkeeper, upon receiving the ball back from a defender, panicked under the pressure of Rashford, kicking only thin air as he tried to clear the ball and allowing the striker to run in and fire into an empty net as United easily booked their place in the next round.