As expected, the hosts were on top from the outset, dominating possession and peppering the Reading goal.
Christian Eriksen and Marcus Rashford each came close to finding the breakthrough from direct free-kicks, and Tom Holmes made a crucial intervention to deny Wout Weghorst from close range.
As the half progressed, there was no let up in United chances with Bruno Fernandes spurning a couple in quick succession, before Rashford pounced on a loose ball, however VAR disallowed the header for an offside in the build-up.
The Royals almost sprung an enormous surprise on the stroke of half time when indecision from Tyrell Malacia allowed Junior Hoilett to pinch the ball in the box, but David de Gea was on hand to deny the visitors a shock lead.
Ultimately, it proved to be a frustrating 45 minutes for the Red Devils, failing to turn their 79% possession and 15 shots into anything tangible.
To their credit, the Championship side made a strong start to the second half, but United’s quality eventually showed.
Antony played an incisive defence-splitting ball through to international teammate Casemiro, who ghosted into the box and nonchalantly lifted over the helpless Joe Lumley.
Still reeling, Reading’s chances of progression were swiftly dealt another blow when Casemiro netted a second in three minutes, bending in an effort from distance.
Having performed admirably, the hinges threatened to come off for Paul Ince’s side, and an avoidable pair of bookings for a frustrated Andy Carroll immediately preceeded a third goal for the hosts, as Fred provided a deft near-post flick.
Fortunately for the travelling fans, substitute Amadou Mbengue nodded in a late consolation from a corner, giving them something to cheer about as they bow out of the FA Cup, while United continue in their pursuit of a first piece of silverware in six years.
Flashscore Man of the Match: Casemiro (Manchester United)
