The England forward’s rich vein of holiday form continued with a magnificent, long-range 84th minute strike that finally beat Scott Carson and ended a long and frustrating wait for that opening goal.

Pogba, whose recent form was the subject of a vehement disagreement between Mourinho and TV pundit Paul Scholes at the start of the week, started the tie as if he still had something to prove to the former Old Trafford legend.

Some early neat footwork on the edge of the Derby area set up Jesse Lingard for a shot which the midfielder planted well over the goal and then the French international threatened the goal himself, receiving Juan Mata’s pass and taking a controlling touch before curling a shot just over from 20 yards.

It was the sort of start Mourinho would have wanted, and expected, when he named a strong side despite making five changes from United’s League win at Everton on Monday.

It was another chance for Henrikh Mkhitaryan, predicted by many to be on his way out of Old Trafford in the January transfer window, to shine although one woefully mis-hit cross drew audible groans from the home fans, and jeers from the 5,400 travelling Derby supporters.

Those visiting fans were briefly inspired when the Rams launched a promising counter-attack for the first time, Tom Lawrence feeding Sam Winnall who had to be halted by an excellent Chris Smalling tackle.

But the game soon settled back into a pattern of United domination with Rashford clearing the bar from 30 yards and then, far more wastefully, from a dozen after he bulldozed his way through Alex Pearce’s challenge.

Mata came close with an excellent free-kick, from the edge of the area, that forced Scott Carson into the game’s first meaningful save as he soared to paw it away with both hands.

That close call prompted Derby into an immediate response with Johnny Russell’s cross picking out Marcus Olsson who crouched to guide a clever header goalwards only for Sergio Romero to make an excellent save as he tipped over the United bar.

Derby, strongly paced in the bid to win promotion to the Premier League, were growing into the game with another couple of half chances falling Winnall’s way in the following exchanges.

But United should have taken a lead into the interval as Rashford wasted two glorious headed openings, nodding a Mkhitaryan cross against the post and then meeting a Mata centre but steering a tame effort directly at Carson.

And Carson made another superb, flying stop from a United free-kick, this time from Pogba whose right-foot shot looked destined for the top left-hand corner until the keeper turned it high around the post.

Mourinho had seen enough of Mkhitaryan’s woeful efforts by the interval, hauling him off for Romelu Lukaku, but the second half might have started with a serious problem for the Reds after Derby won a free-kick on the by-line.

Daley Blind failed to clear Lawrence’s cross and the ball broke for Tom Huddlestone who unleashed a promising drive that was deflected out for a corner.

The presence of Lukaku made United a more threatening prospect, however, and Mata soon tested Carson with an 18-yard effort the keeper could only parry although Lukaku’s follow-up was blocked and Pogba rolled the rebound wide.

As United continued to take their attempted shots statistic well into the 20’s, Rashford could not believe it when his ferocious strike after 71 minutes beat Carson but struck the inside of the post and flew to safety.

And when Lingard was denied by yet another Carson save, Pogba missed the target from 15 yards from the ricochet, with the Derby keeper stranded.