The 20-year-old signed for the Red Devils in January and is set to complete an £8million move over the summer.
Smalling is delighted to hear that his new boss has complete faith in his ability and is determined to show why he is so highly rated.
"I'll definitely be starting on the front foot in terms of a first-team place," he told the Fulham Chronicle.
"Sir Alex sat me down and explained where I am and where I'll be going.
"You start off the season just hoping to get as many games as you can and then you get an opportunity like this, and yeah, it does bring pressure.
"But it's a compliment and a chance to show what you are worth, and hopefully I can repay it."