Ferguson signed Zaha for £15m in the biggest deal of the window but has loaned him back to Crystal Palace for the rest of the season.
The Mirror says Ferguson has called Zaha to warn him he must keep up his exciting form at Palace.
He made it clear that he expects Palace starlet Zaha to maintain his form and not let up - even though he knows he is leaving in the summer.
The Scot also prides himself on his players keeping up the highest standards - and made it very clear what he wants from a United player and says Zaha must behave like an "ambassador."
Zaha has a reputation as a religious and very professional young man, and was quick to assure Ferguson that he will embrace his new club's standards.