Reading exited the FA Cup Third Round at Old Trafford for the second time in three years after a two-first half goals secured victory for United.
A penalty from Juan Mata put the 12-time FA Cup winners in front on 22 minutes, after a VAR decision confirmed an Omar Richards foul on the Spanish midfielder.
Reading came close through Andy Yiadom towards the end of first period, with his shot on the turn nearly catching out Sergio Romero at his near post. However, Romelu Lukaku doubled United’s lead on the stroke of half-time after Alexis Sanchez pounced on error by John Swift in midfield to play the Belgian striker through on goal.
Reading showed no sign of nerves and saw plenty of the ball in the opening exchanges, but United were the first to threaten with Scott McTominay, who headed goalwards from a free-kick but returning Royals skipper Liam Moore was in position to head it away.
Sanchez then fired narrowly over for the hosts, after Lukaku broke through the middle.
At the other end Garath McCleary raced down the left for Royals, before squaring across the box to find Andy Yiadom, but his effort skewed harmlessly over the bar.
The ball was then put into the Reading net by Fred, but the linesman flagged for offside.
However, after a lengthy VAR deliberation, a penalty was awarded for a foul in the build-up on Mata by Richards.
Mata stepped up and sent Jaakkola the wrong way, to put United ahead on 22 minutes.
Royals looked to respond and nearly did when Callum Harriott released Danny Loader, but the 18-year-old was eventually dispossessed as he attempted to tip toe around Romero in the United goal.
Reading continued to press and John Swift did well to win the ball back on the edge of the United area, and pick out Harriott, but his shot was too close to Romero to cause any problems.
As the break neared, the visitors continued to pose a threat with Yiadom going close after a patient passing move ended with the Royals right-back producing a fine effort on the spin which Romero had to parry out for a corner.
It was a heart-breaking end to the first half for Royals, who conceded in injury time after Swift lost it in midfield and Sanchez threaded it through to Lukaku, who neatly rounded Jaakkola before slotting home United’s second.
Royals boss Jose Gomes opted for a change at the break with Tiago Ilori, who received treatment after a strong challenge earlier in the game, being replaced by Sone Aluko.
After the restart, Swift tried his luck from a free-kick from range, but his strike was straight into the arms of Romero.
Another Royals chance came and went when Aluko played through Harriott, whose effort on goal was sweetly-struck, but again was too close to the United keeper.
Jaakkola prevented a third for United when he got down well to deny the recently-introduced Fellaini after Ashley Young had wriggled his way through the Royals defence and played the ball across from the left.
A slip by Young on the ball nearly enabled Royals to pull one back, with sub Modou Barrow releasing Aluko, who fired at goal from the edge of the area, with Romero blocking around the post for a corner.
Jaakkola palmed away a stinging effort from Andreas Pereira late on as United secured a safe passage into the hat for the fourth round and left Reading winless in 11 games.
READING: Jaakkola; Yiadom, Ilori (Aluko 45), Moore (c), Richards; Kelly, Rinomhota; Harriott (Meite 76), Swift, McCleary (Barrow 61); Loader.
Subs not used: Walker, Gunter, O’Shea, East.
Yellow card: Yiadom (33)
MAN UTD: Romero; Dalot, Darmian, Jones, Young (c); Pereira, McTominay, Fred (Fellaini 61); Mata (Chong 61), Sanchez (Rashford 63); Lukaku.
Subs not used: Grant, Lindelof, Garner, Martial.
Goals: Mata (22 pen), Lukaku (45+4)
Yellow card: Chong (77)
Referee: Stuart Attwell
Attendance: 73,918
