The Frenchman, who had been linked with a possible transfer window move to Barcelona, said he remained hungry for more success.
Mourinho told Sky Sports on the tough decisions he faced when making substitutions: "A match where I needed six changes not three".
And afterwards the new world champion vowed to always work hard "for the people that trust me".
Having returned from France's triumph in Russian Federation last month to intense media speculation about his future under United manager Mourinho, the 25-year-old Pogba was named skipper of a team that included debutant Fred.
"We play against a team that invest more than us".
It was a great start from United as within the first 2 minutes they had a penalty. United looked bright for a brief period after the first goal went in but Leicester worked their way back into the game and really started to press, with a few attacks in quick secession down the left side.
However, he can still rely on one of the world's best goalkeepers as David de Gea put his poor World Cup showing behind him with a fine save to prevent Maddison levelling.
Vardy pulled a goal back for Leicester in stoppage time to give them some reward for a good performance against last season's runners-up. "They spent more money..."
Vardy almost made a vital contribution as provider when he outmuscled Shaw and picked out Gray in the middle who was denied by another fine save by De Gea.
He was handed the captain's armband against the Foxes and set United on their way to a 2-1 victory with an early penalty - but appeared to allude to off-field issues in a post on his social media accounts after the game. So it was not easy to manage the game by the touchline point of view.
"We don't have a penalty-taker: it's how we feel, and I made a decision to take it".
Reflecting on his first United strike, Shaw admitted he hit a career high under the lights at Old Trafford and is desperate to repeat the feeling over and over again.