The Man United captain has faced heavy criticism following his disappointing start to the season and Mourinho opted to deploy Juan Mata in the No.10 role instead.
Mourinho’s side were spectacular in his absence, scoring four goals in the first-half and nailing the defending champions into the ground.
Speaking after the game, Smalling claimed Rooney’s dropping from the starting XI did not change him.
“Wayne did not appear down. He was the same before the game when we were all getting ready. He is often one of the most vocal and he was the same,” he said.
“Whatever the situation is, whatever game, whether he is on the bench or playing or whatever, he is always that same type of character and that is why he is England’s main man and our main man.
“He is a very experienced guy and he has played that many games that I think it will only be a matter of time before he is back in there and firing again because he’s quality.”
Mourinho offered his backing to Rooney after the game, stating he still completely trusts the Englishman as the club’s captain.
He has a vital role to play at Old Trafford but his time as an automatic starter will soon come to an end after over a decade in the squad.
It’s sad to see him left on the bench, but there are currently other players on the squad that have more to offer and it’s just the way football works.