The England Under-21 star has endured a rough start to life at Manchester United, featuring only sparingly for the Premier League champions, but Juan Mata's arrival has given the former Crystal Palace man the chance to prove himself in the top flight with a loan move to the Bluebirds.
Former Eagles boss Holloway, who coached Zaha at Selhurst Park, believes the youngster has struggled to adapt to the step up in quality and has challenged him to show his true ability.
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"I hope he uses his sabbatical in South Wales to show United exactly what they are missing.
"Believe me, he is one helluva player. And he is also a terrific lad, a manager's dream, in my experience. So, I was surprised by reports during the week that he had been dropped to the bench for a reserve game because he turned up late.
"That isn't the Wilfried Zaha I know and I am sure that he would not have shown such a lack of respect to his club on purpose. But, as a manager, I can't condone any player failing to get to a game on time.
"And, again, it's all about attitude. Or lack of attitude.
"I will always be grateful to Wilf for the role he played in helping Palace to win promotion to the top flight when I was the manager at Selhurst Park.
"And that's why I have his best intentions at heart when I say the time has come for him to take stock of his life and career and grow up a little bit.
"Because, believe me, there is nothing more tragic than unfulfilled potential."