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.