On top of the quick turnaround from the World Cup in Russian Federation, a shortened transfer window that closes 24 hours before the season kicks off has left many teams scrambling to get stronger at the last minute - none more so than Manchester United.
United were awarded a penalty in the opening two minutes when Daniel Amartey handled the ball, and after Pogba tried to take the ball to the spot, he was met by an insistent Sanchez.
After a week in which Pogba has been linked with a move away from Old Trafford, with Barcelona's interest piqued by the Frenchman's frosty relationship with Mourinho after he was repeatedly dropped last season, the Portuguese showed his faith in the midfielder by surprisingly handing him the armband.
Leicester responded well though with new signing James Maddison forcing a fine save out of United keeper David De Gea as the visitors gave Mourinho's side plenty to think about.
Vardy pulled one back in stoppage time after Ricardo Pereira's cross came back off the post.
"Pogba was a monster, we thought maximum 60 minutes, he managed (more than) 80", Mourinho said after taking his captain off late in the game. "Paul was fantastic. His contribution was incredible".
Manchester United endured a poor summer this time around.
Schmeichel was called into action again 10 minutes into the second half, going low and to his left to keep out a Matteo Darmian line drive from distance as both teams looked to up the tempo of the match after the break. Can Paul Pogba get the best out of Paul Pogba? Eric Bailly did superbly to deny Iheanacho, and Vardy bundled Shaw off the ball to send in a cross that Gray nearly flicked home.
The Guardian reports that Mourinho's wishlist was vetoed by United as there were concerns that "he should not be allowed to get his way if it meant potentially wasting tens of millions of pounds on a short-term fix".
"Pogba was a monster", said Mourinho.
Leicester manager Claude Puel: "We lost Riyad Mahrez, who was a very valuable player for us, so it was important to keep our best players and have good additions to the squad. Every team is a good team, forget the name, forget the history, forget the shirt". "In this condition it has been a good performance".