Ian Holloway has questioned the 'attitude' of former charge Wilfried Zaha ahead of the 21-year-old's prospective loan move to Cardiff City.
Holloway, who coached Zaha at Crystal Palace before the talented winger moved to Manchester United this season, claimed the England international has "more natural talent than any footballer I have played with or managed".
But the former Crystal Palace and Blackpool manager warned Zaha that he must start growing up and quickly show why United paid £15million for him midway through last season, otherwise he could be labelled "a waste of money".
"Wilf has gone from being a big fish in the small pond of the Championship and is now a minnow in the shark-infested waters of the Premier League," Holloway wrote in his column for the Sunday Mirror.
"And it's been a struggle.
"I hope he uses his sabbatical in South Wales to show United exactly what they are missing.
"Believe me, he is one helluva (sic) 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."
Holloway expressed regret at not preparing Zaha more ahead of the latter's move to United but claimed the Ivory Coast-born winger could not blame anyone else for his lack of playing time at Old Trafford.
"I wish now that I had taken him to one side after a Crystal Palace training session and warned him that it (the United transfer) wasn't the end of his journey to the top of the game, it was just the first step," the 50-year-old said.
"Wilf is joining Cardiff on loan after playing just 28 minutes of Premier League football in five months at the champions under David Moyes.
"No doubt, some people will now label the lad a waste of money. But... Wilf has got the world at his feet.
"At the age of 21, he has more natural talent than any footballer I have played with or managed during a lifetime in the game. What he has got to prove now is that he also has the temperament.
"Wilf has only one person to blame for the fact that his only start in the famous red shirt so far was a Capital Cup tie against Norwich in October: Himself.
"He hasn't been a regular in the United team simply because he hasn't done what his manager has demanded from him."
|Furious Mancini slams Inter´s ´worst ever´ first half against Lazio|
|Serie A Review: Champions League places locked, Milan play out six-goal thriller|
|La Liga Review: Villarreal secure Champions League return|
|Lazio 2 Inter 0: Champions League race comes to a Klose|
|Koeman delivers Pelle warning|
|Morata wants to stay at Juventus, claims Marotta|
|Pellegrini disappointed with City defending in defeat|
|Iheanacho: City will bounce back from Saints defeat|
|´On fire´ Mane salutes Southampton show|
|Angers 0 Marseille 1: Batshuayi strike secures Ligue 1 status|
|Southampton 4 Manchester City 2: Mane hat-trick blows top-four race open|
|Van Gaal calls for video referees after Drinkwater decision|
|Schmeichel: I don´t care how we win it|
|Montella open to Italy role|
|Brocchi pleased with Milan fightback|
|Van Gaal defends ´human´ Fellaini over Huth elbow clash|
|Ronaldo wants Zidane to stay at Madrid|
|Ranieri to miss decisive Tottenham clash|
|Rooney disappointed after Leicester draw dents top-four hopes|
|Bayern Munich v Atletico Madrid: Hosts seek to vent Bundesliga frustration|
|Leicester captain Morgan hails battling Old Trafford point|
|AC Milan 3-3 Frosinone: Menez penalty denies strugglers|
|Klopp not concerned by Sturridge behaviour|
|Manchester United 1 Leicester City 1: Captain Morgan on target as Foxes edge closer to glory|
|Allofs: We do not have the same weapons as Bayern|
|Guidolin coy on Swansea future|
|Allegri happy with win after title celebrations|
|Umtiti flattered by Tottenham interest|
|Klopp frustrated by lacklustre Liverpool|
|Hannover mourn Feierabend|
|Godin, Carrasco fit for Bayern clash|
|Swansea City 3 Liverpool 1: Ayew double punishes wasteful visitors|
|Dybala claims Messi, Ronaldo would score less in Italy|
|Juventus 2 Carpi 0: Hernanes, Zaza on target as champions march on|
|Ronaldo back in training for Madrid|
|Barcelona confirm Bravo calf injury|
|Aulas brands Ligue 1 ´championship of Qatar´|
|Leicester City at Manchester United: Aiming for Hollywood ending to title push|
|I can start for England at Euro 2016 - Sturridge|
|Dybala never doubted Juventus|
|Aguero celebrates brother´s Independiente debut|
|Sturridge rounds on critics, plays down Klopp rift|
|Adelaide United 3 Western Sydney Wanderers 1: Reds seal maiden A-League title|
|Eriksson: Simeone is an example to follow|
|´Where am I?´ - Lovren reveals travel struggles|
|´If I have to leave Bayern, then I will´ - Benatia|
|Walker ´over the moon´ after Pochettino agrees new deal|
|MLS Review: Villa leads City, Impact held|
|We´d probably be relegated without Defoe – Allardyce|
|Koeman: Leicester will do well in Champions League|
|Ronaldo needs rest or could miss Euros - doctor|
|United shaped me as a player - Schlupp|
|Sanchez, Vidal lead Chile´s Copa squad|
|Arsenal´s patience paid off - Cech|
|I will know Madrid´s plans - Pellegrini|
|Granada 3 Las Palmas 2: Superb comeback boosts hosts´ survival hopes|
|Martinez pleased with impact of new faces|
|Ligue 1 Review: Lyon, Monaco continue fight for second|
|Serie A Review: Fiorentina frustrated, Torino hit five|
|Barca keeper Bravo set for tests on calf strain|
|Barca will not rely on rivals slipping up - Luis Enrique|
|Simeone: I am not a fortune teller|
|Neil defiant in defeat|
|Real Betis 0 Barcelona 2: Rakitic and Suarez edge champions back ahead in title race|
|´Protests more like disappointed love´ - Wenger sorry he cannot keep Arsenal fans happy|
|Bundesliga Review: Monchengladbach and Dortmund delay Bayern´s title party|
|Arsenal should be doing better, concedes match-winner Welbeck|
|Black wants Villa display to build bridges|
|Tuchel: Hummels abuse went too far|
|Flores laments mixed Hornets performance|
|Scottish Premiership Review: Celtic made to wait by Aberdeen|
|Ribery a doubt for Bayern´s crunch Atletico clash|
|Arsenal 1 Norwich City 0: Substitute Welbeck boosts under-fire Wenger|
|Allardyce rues Sunderland nerves after Stoke draw|
|Atletico Madrid 1 Rayo Vallecano 0: Griezmann maintains title momentum|
|Benitez salutes Newcastle ´heroes´ Townsend and Darlow|
|Hughes disappointed by Sunderland penalty call|
|Football League Review: Wigan confirm promotion to Championship|
|Bilic confident of Europe after West Brom win|
|Howe defends players´ efforts after form slump|
|Bale can match Ronaldo´s run - Zidane|
|Watford poor in Villa win, concedes Deeney|
|Hummels slams ´nonsense´ claims over Bayern request|
|Zidane hopeful on Ronaldo, Benzema as Madrid give backing to medics|
|Pardew rues Cabaye penalty miss in defeat to Newcastle|
|West Brom did not get the breaks - Pulis|
|Fan protests of no concern to Martinez|
|Ramos urges Real Madrid to ´fight to the end´|
|Defoe: You haven´t got a choice, I had to score|
|Watford 3 Aston Villa 2: Late Deeney double sinks Villa|
|Stoke City 1 Sunderland 1: Defoe snatches point but Allardyce´s men slip into bottom three|
|Real Sociedad 0 Real Madrid 1: Late Bale winner keeps title challenge alive|
|West Brom 0 West Ham 3: Noble brace boosts European hopes|
|Newcastle United 1 Crystal Palace 0: Townsend, Darlow heroics boost Benitez|
|Everton 2 AFC Bournemouth 1: Baines strike eases pressure on Martinez|
|Leno to stay at Leverkusen after buyout clause expires|
|Bayern Munich 1 Borussia Monchengladbach 1: Hahn puts title celebrations on hold|
|Borussia Dortmund 5 Wolfsburg 1: Fans round on Hummels but title hopes remain|
|Watzke won´t give up on keeping Hummels|
|Pepe tips Zidane to become top coach|
|Allegri and Mancini laud Ranieri´s Leicester heroics|
|Allegri still hopes to keep Morata at Juventus|
|Mancini praises ´top-quality´ Banega|
|´Even Guardiola needed time´ - Brocchi has no regrets over taking AC Milan role|
|Willian desperate for next season to arrive|
|Mancini: Inter season not a disaster|
|Chelsea v Tottenham: Pochettino hopes derby motivation keeps title chase alive|
|Crotone not Italy´s Leicester, says director Ursino|
|Klopp: Flanagan still faces fitness battle|
|Manchester United v Leicester City: Ranieri aiming for Hollywood ending to title push|
|Hummels to Bayern is the logical deal - Hitzfeld|
|Shaw pushing for United comeback this season|
|Sportiello ´proud´ to be linked with Napoli|
|Arsenal must change to end title drought - Cazorla|
|Tete can´t confirm Bayern interest|
|Montero, Valencia set for Copa America Centenario|
|Vardy, Mahrez more important than Leicester´s defence - Martinez|
|Pellegrini blasts ´unbelievable´ Premier League fixtures|
|Standard Liege terminate Valdes´ loan deal|
|Hiddink: Leicester will not disappear|
|Mata: Leicester can wait a week|
|Pizarro, Farfan not included in Peru´s 40-man Copa squad|
|Wenger: My loyalty helped build Emirates|
|Pochettino eyes Ferguson legacy at Tottenham|
|Thompson to leave Melbourne Victory|
|New York Red Bulls 4 FC Dallas 0: Hosts make it two in a row|
|Blanc hails ´motivated and disciplined´ PSG|
|Van Gaal: Easier for Leicester to sign players than United|
|No shocks as Paraguay announce provisional Copa squad|
|Suarez headlines Uruguay´s Copa America squad|
|Sturridge reveals he is ´not Liverpool for life´ and hopes to match Suarez success|
|David Luiz, Silva and Marcelo absent from Brazil´s preliminary Copa America squad|
|Augsburg 0 Cologne 0: Weinzierl´s men edge closer to survival|