Marcus Rashford announced himself in the Jose Mourinho era at Manchester United with an injury-time winner to sink gallant Hull City 1-0 at the KCOM Stadium.
Rashford did not play a minute in United's opening two Premier League wins this season and was dropped down to England's Under-21s this week ahead of Sam Allardyce naming the first senior squad of his tenure.
But, with his side looking set for an evening of rain-sodden frustration in the face of a phenomenal Hull resistance, Mourinho turned to the livewire 18-year-old, who converted a Wayne Rooney cross from close quarters moments after David Meyler threatened victory by blazing over for the hosts.
United join early pacesetters Chelsea on nine points at the summit of the fledgling top-flight standings, three points ahead of Hull, whose vice-chairman Ehab Allam confirmed the club's takeover has reached the due diligence stage in his programme notes
Former Old Trafford number two Mike Phelan has overseen tremendous on-field achievements so far with meagre resources and will hope the conclusion to that protracted process can help him bring in reinforcements before next week's transfer deadline.
Goalkeeper Eldin Jakipovic and captain Curtis Davies were among the heroes in a gruelling finale for City that would end in heartbreak.
Impressive early season form, along with Hull's still remarkable lack of alternatives, saw both teams start the match unchanged and the hosts had to clear early danger when Zlatan Ibrahimovic ingeniously brought down an Antonio Valencia cross that appeared to be sailing beyond him.
Ibrahimovic sent a 10th-minute header drifting narrowly over as he again made himself an imposing presence in the Hull area, but Phelan's side played with increasingly familiar poise.
Robert Snodgrass fired a free-kick narrowly wide, with United goalkeeper David de Gea a spectator after Marouane Fellaini had been booked for a clumsy foul on Adama Diomande.
Snodgrass took a painful whack for his troubles when Luke Shaw bravely stopped him from converting a superb cross by Andrew Robertson - the Hull left-back who was alert to block Valencia from close quarters at the other end.
There was nothing Robertson could do as Juan Mata deftly shimmied around him in the 37th minute, drawing a sharp save from Jakupovic before Davies got in the way of Wayne Rooney's follow-up on the goalline.
A sprawling Jukupovic was relieved to see Ibrahimovic backheel into the side-netting after touching a Mata free-kick around him and the deadlock remained intact at the interval.
Snodgrass, whose last Premier League campaign was decimated by a serious knee injury, remained in discomfort and he slumped to the turf within a minute of the restart, making way for Shaun Maloney.
Both teams exchanged pleasing passages of possession that lacked penetration early in the half but United started to push Hull back more consistently around the hour, Ibrahimovic's snap shot fizzing wide from the edge of the box.
Rooney volleyed just wide when a Valencia cross was partially cleared but, on an increasingly rare Hull attack in the 75th minute, Tom Huddlestone saw a drive skid past the post when a deflection off Eric Bailly left De Gea wrong-footed.
Rashford injected the type of verve from the bench that was beyond Hull and a piercing run into the box drew Jakupovic's finest save of the match.
But Jakupovic was finally beaten when Rashford tapped home from a squared Rooney pass in stoppage time.