Ruud van Nistelrooy may never lead Manchester United in the cup competition again and will therefore end up on the right side of a 5-2 goal fest as the interim manager can warm up his dotage.

Two from Casemiro – the opener was a screamer – and Bruno Fernandes plus one from Alejandro Garnacho swept away Erik ten Hag’s dismal period, and are a fitting gift for Ruben Amorim should he be present for Chelsea’s visit on Sunday.

With United pushing to appoint Sporting’s head coach as Ten Hag’s permanent successor, Van Nistelrooy’s spell will come to an end once the bickering over the shortening of the 39-year-old’s 30-day notice period comes to a close. But if Sunday is still too early, Van Nistelrooy will be more than happy to push his way past Enzo Maresca’s fifth place.^­positioned team.

Van Nistelrooy, smartly dressed in a turtleneck, dark jacket and trousers, laid out his manifesto to face Leicester, who reached two points and a place – 15th – below United in the league: “Hopefully a lot of ball possession and attacking. That’s what Man United stands for.”

Joshua Zirkzee, one of the three substitutes, was able to do exactly this when he came in, but as was the fault line in his game, the wrong option was chosen and the Foxes escaped.

But then Casemiro’s lightning bolt caused Van Nistelrooy to ‘oooh’ and raise his arms. United’s build-up was neat, Leicester’s lack of pressure was an oversight. On an inside left channel, Lisandro Martínez found Alejandro Garnacho, who skipped the infield and tagged Bruno Fernandes. The captain, as he does cutely, let the ball roll and the Brazilian was of age to fire past Danny Ward into the top right corner.

This broke an atmosphere that had strangely calmed down, a mood that soon settled down again for a while. Then a second strike stirred emotions again. Casemiro initiated the attack this time and located Dalot on the right. He shifted his body towards the ball and cut in a cross that was punched in by Garnacho.

Cut to an anguished Steve Cooper in his technical area, shown a yellow card for protests that Dalot was offside – and his desperation almost increased when Fernandes lined up a shot from the edge of the area. But the No. 8 opted for a no-look pass instead and sent it the wrong way.

Since Sir Alex Ferguson retired in May 2013, United have become experts at shooting themselves into the proverbial box. This did not change under their second Dutch manager of the season: Altay Bayindir, the third of United’s new staff, flapped at a cross, the ball went to Bilal El Khannouss who scored via pinball from the left post.

The prospect of another United collapse lasted six minutes – the period in which Fernandes and Casemiro registered. El Khannouss tripped over Garnancho and Fernandes turned a deflected free-kick past Ward; Casemiro then hit the rebound off both Leicester posts – their left first – after his own header from a Rashford throw.

All fine and dandy for United until a Casemiro/Dalot mix took place in first-half extra time and Conor Coady stepped in to give Van Nistelrooy something to chew on during the break.

Despite the caretaker fielding a second number six in Manuel Ugarte, the holes in the United midfield that are an unwanted legacy from Ten Hag remained and Cooper’s unit ran through them in several worrying attacks.

Van Nistelrooy, on a technical level, met this and other sloppy United play with obvious disquiet. Worst of all, James got behind Justin and crossed, blocking a swinging Casemiro and, in the ensuing corner, sending the latter on his way to safety.

More came, often from the boots of firefly El Khannouss, whose clever wing play left United in disarray. Then, finally, a slick United attack in the half that ran through Fernandes-Rashford-Fernandes-Zirkzee-Garnacho and ended with a Zirkzee fingertip-warmer for Ward.

And then came United’s fifth-place finish. A Fernandes-Rashford combo caused a brain freeze for Caleb Okoli, leaving Fernandes clean through. A dummy took Ward to the ground and the 30-year-old would never miss from an inch away.

United has cruised. Rashford and Martinez followed, Amad Diallo and Noussair Mazraoui. Ugarte, United’s Red Adair, turned into a schemer who turned and sprayed an aerial ball to Fernandes on the left. For United it was something rare: evenings like this.