Substitutes Marcus Rashford and Marouane Fellaini struck as Manchester United beat Leicester City 2-0 to continue their 100 per cent start to the Premier League season.
Rashford finished from Henrikh Mkhitaryan's corner three minutes after coming on, just as it looked like Jose Mourinho's men – who had seen Kasper Schmeichel save Romelu Lukaku's penalty – would have to settle for a frustrating home draw that typified last season's top-flight struggles.
Fellaini, another of Mourinho's introductions from the bench, then netted with eight minutes remaining to seal victory, although it looked like he was offside as he converted a shot from United's other sub, Jesse Lingard.
United were unable to make a first-half breakthrough despite being on top, Juan Mata having a goal disallowed for offside shortly before drawing a stunning save from Schmeichel.
After the break, Lukaku had a penalty kept out by the impressive Schmeichel, who achieved a feat his father Peter never managed at Old Trafford in saving a Premier League spot-kick.
Sprint legend Usain Bolt was in the stands wearing a United cap and scarf as his beloved side moved back to the top of the table with nine points from their first three games, in which they have kept a trio of clean sheets.
Leicester, meanwhile, have three points from their opening three fixtures having also lost away to Arsenal in a tough start to the 2015-16 champions' campaign.
United were completely dominant in the first half and had a goal disallowed for offside in the 18th minute.
Lukaku's shot was parried by Schmeichel and converted by Mata on the rebound, only for the assistant to disallow the strike in a marginal call, much to the frustration of the Spain international.
Paul Pogba slid in and fired inches wide from Anthony Martial's left-wing cross as the hosts kept up the pressure, before Mata was again denied, this time by a magnificent one-handed Schmeichel save to keep out his curling effort.
Leicester tested David de Gea for the first time when Shinji Okazaki fired in an effort from 25 yards, before Pogba sent two searing 30-yard strikes inches off target for United as the match reached the break level.
United won a penalty after 53 minutes when, seconds after a handball claim against Harry Maguire was denied, referee Michael Oliver pointed to the spot after Danny Simpson blocked Martial's cross with his arm.
But Lukaku was unable to beat the inspired Schmeichel from 12 yards, the Leicester goalkeeper diving to his right to beat away the Belgium international's effort.
1 - Kasper Schmeichel (1) has now saved more Premier League penalties at Old Trafford than Peter Schmeichel (0). Eclipsed. pic.twitter.com/ILSOPPPQBi— OptaJoe (@OptaJoe) August 26, 2017
De Gea kept out Riyad Mahrez from a tight angle when Leicester had a rare venture forward at the other end, after which Foxes manager Craig Shakespeare introduced Demarai Gray and Andy King from the bench.
Mourinho made his first move by bringing on Rashford for Mata and the England international had the desired impact, netting in the 70th minute.
Mkhitaryan's corner found its way to the forward 10 yards out and his low effort was enough to see Schmeichel finally beaten.
The Portuguese boss also brought on Fellaini and Lingard from the bench and that duo combined as United sealed victory.
Lingard worked an opening on the left and shot at goal, with Fellaini prodding in from close range despite appearing to be beyond the last defender.
King almost pulled a goal back in stoppage time after getting on the end of Gray's cross, but De Gea was alert to deny him at point-blank range as United went into the international break on a high.