Marcus Rashford struck a stoppage-time winner to sink battling Hull as Manchester United maintained their 100 percent start in the Premier League under Jose Mourinho.
The United teenager, a second-half replacement for Juan Mata, turned home Wayne Rooney's slide-rule pass for the only goal of the game in the second minute of time added on to finally break Hull's brave resistance and send the newly promoted club to their first defeat of the season.
It was a tough pill to swallow for Hull, who would have deserved a point for their sheer endeavour had they managed to hold on, but United's patience was finally rewarded and it is they who join Chelsea at the top of the table.
Such was Hull's tenacity and discipline, especially on the edge of their penalty area, United found chances hard to come by in the first half.
Zlatan Ibrahimovic headed just over the crossbar from Anthony Martial's cross in the 10th minute, while Hull passed with precision on the counter-attack, one of which ended with Marouane Fellaini being booked for his foul on Adama Diomande within striking distance.
Robert Snodgrass curled the resulting free kick just wide and was then inches away from latching on to Andy Robertson's superb cross at the back post.
United hogged possession and probed patiently, but were able to fashion very little with it. Juan Mata's 33rd-minute free kick was easily gathered by Eldin Jakupovic and at the other end David de Gea was forced into a diving catch from Abel Hernandez's header.
Rooney went close to breaking the deadlock for United in the 36th minute, but his shot was blocked by Hull skipper Curtis Davies close to the goal line.
United threatened again as half-time approached, but after he had guided Rooney's through ball away from Jakupovic at full stretch, Ibrahimovic's audacious backheel found only the side-netting.
Snodgrass, who collided with the post following his lunge to get on the end of Robertson's cross and required treatment, was replaced by Shaun Maloney three minutes into the second half.
Hull found themselves increasingly pegged back after the break but retained their shape and their composure as United's threat was snuffed out on the edge of the area.
Mourinho sent on Henrikh Mkhitaryan, yet to make his first start for United, for Martial on the hour mark, while Ibrahimovic's frustration was evident after Mata nicked the ball off him on the edge of the box only to lose control.
United fans appealed for a penalty when Valencia's cross hit David Meyler's shoulder and Rooney pulled a low right-footed shot wide before Tom Huddlestone twice threatened in quick succession for Hull.
The midfielder's first shot from outside the area was deflected wide off Eric Bailly and from the half-cleared corner which followed, he fired just off target.
Pogba curled a tame free kick wide before Marcus Rashford, a 71st-minute replacement for Mata, forced a fine one-handed save from Jakupovic after jinking into the area and shooting low towards the bottom corner.
United were camped in Hull's half as the game drew to a close and when the ball fell to Mkhitaryan inside the area Davies won a standing ovation from the home fans by hurling himself in front of the midfielder's goalbound shot.
Meyler almost snatched it for Hull in the dying moments as he fired over, but United broke free down the other end and Rooney took the ball past Elmohamady to the byline and slipped an inch-perfect low cross into Rashford's pass for the substitute to tap home the winner from two yards.