Manchester United will expect Amad to make a “significant impact” despite his age according to Owen Hargreaves.
The teenager arrived in Manchester last month having been signed from Atalanta in the summer.
In his short time at the club he has already made his mark on the U23s – scoring twice on his debut against Liverpool.
Ole Gunnar Solskjaer handed him his debut off the bench in United’s Europa League win over Real Sociedad on Thursday night.
Amad is only 18, but his £38m price tag shows that the Red Devils have high hopes for his future.
The Ivorian’s role as a wide forward has led to suggestions that United will no longer pursue Jadon Sancho.
Although Hargreaves sees the duo at different stages in their development.
He said on BT Sport: “Well when you sign a player for that amount of money you want them to have an impact
“Obviously they believe in him which is why he was on the bench today and why he came on.
“Martial and Rahsford are setting the levels for what it needs but I think for the money they’ve paid they’re going to want a significant impact.
“I think Jadon Sancho, that category if player is already established whereas Diallo is just on the start and hopefully got a special future.”
Sancho had been United’s top transfer target last summer but they were unable to get a deal over the line.
Borussia Dortmund were looking to receive north of £100m for the Englishman, but have since cooled their stance and may be willing to offload him for less, according to reports in Germany.
Solskjaer is keen on bolstering his forward line, but his arrival could hamper the development of Amad or Mason Greenwood.
Dortmund will also have to fend off interest in Erling Haaland and are unlikely to let both players, if any, go.