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."
|PSG unhappy over €100,000 fine after damage at Lyon|
|Toronto FC 2 Houston Dynamo 0: Altidore at the double for in-form MLS hosts|
|Toure: Hopefully United attack more next season|
|Conte can´t guarantee Hazard stay as Madrid circle Chelsea star|
|Allegri: Juventus´ draw with Atalanta the perfect preparation for Monaco tie|
|Too much, too soon? - Lampard questions Guardiola´s demands at Man City|
|Atalanta 2 Juventus 2: Last-gasp Buffon error proves costly|
|Cardiff City 0 Newcastle United 2: Atsu and Hayden keep title dreams intact|
|Mbappe will go to Arsenal but Henry comparisons premature, says Gunners legend Pires|
|Koeman: Everton need more players with Lukaku´s mentality|
|Tuchel ushers Dortmund back to the well after Bayern triumph|
|Conte impressed by ´four or five´ of Chelsea´s FA Youth Cup winners|
|Pochettino sets Spurs sights higher than finishing above Arsenal|
|Tottenham to move to Wembley for 2017-18|
|Simeone not interested in Jese´s Griezmann jibe|
|Griezmann wouldn´t get in Real Madrid team, says Jese|
|Praise for Lukaku but Chelsea boss Conte happy with Costa|
|United ´miss belief´ but Mourinho gunning for top honours next season|
|Manchester derby draw changes nothing for Liverpool - Klopp|
|Ronaldo so good he could play anywhere - Zidane|
|Barcelona boss Luis Enrique expects Neymar to keep his cool|
|Rooney in midfield, Mourinho and Tuanzebe at centre-back - Manchester United boss assesses injury cr|
|Madrid rotation policy not unjust - Zidane|
|Ancelotti insists he has full support at Bayern|
|Iniesta misses training ahead of Espanyol v Barcelona derby|
|Sanchez trolled by Leicester defender Huth over throw-in controversy|
|Thiago determined to win Champions League after pledging future to Bayern|
|Sanchez throw-in reaction not embarrassing, insists Wenger|
|Lovren pens long-term deal at Liverpool|
|Arsenal scouted Alli before Tottenham move, claims Wenger|
|Thiago signs new Bayern Munich deal|
|Mourinho and I often speak, reveals Evra|
|Barcelona and Real Madrid would find Premier League tough, says Klopp|
|My heart is in Italy, says Chelsea boss Conte|
|Copa Libertadores Review: Barrios hat-trick ensures Gremio stay unbeaten, River preserve perfect rec|
|Ancelotti future not discussed – Rummenigge|
|Mourinho: City will finish in the top four|
|Sevilla boss Sampaoli to be offered Argentina job, confirms AFA|
|Kovacic content at Real Madrid – agent|
|Bilic hails reported West Ham target Sturridge|
|Ramos open to presidential role at Real Madrid|
|Guardiola laments City´s ageing full-backs|
|Mourinho: Aguero very smart in Fellaini dismissal|
|Kompany: United never made it difficult for City|
|Carrick sees point gained for United in Manchester derby draw|
|Manchester City 0 Manchester United 0: Mourinho´s 10 men hold on after Fellaini madness|
|Sevilla 2 Celta Vigo 1: Ben Yedder turns up the heat on Atleti|
|Retiring Lahm wants to have fun in final weeks of career|
|That´s the luck you need - Bender plays down incredible Pokal clearance|
|Rashford starts Manchester derby for United, Gabriel Jesus on City bench|
|´Overrated´ Pogba and Balotelli have been lucky, says Cassano|
|Atletico Madrid not afraid of Real Madrid, Torres claims|
|Chelsea captain Terry wanted at Bournemouth|
|Schneiderlin fires ´revenge´ warning to Chelsea|
|Dortmund-themed cast cheers Bartra as recovery continues|
|Barton betting ban was ´shortest possible sanction´ - FA|
|Eriksen insists Tottenham can still win Premier League|
|Liverpool confirm Gerrard will take over Under-18s|
|Albania fined by FIFA after crowd unrest in Italy|
|Bartomeu to stand trial over Neymar transfer after appeal is rejected|
|Sanchez the only Arsenal player who would get in Tottenham team, says Henry|
|Clement confident of Swansea survival|
|Aguero bemoans City´s bad luck in ´tough year´|
|Barcelona tried to lower Suarez price after Chiellini bite, claims ex-Liverpool CEO|
|Allegri refusing to let Monaco be a distraction in Juve´s title bid|
|Being benched not a problem for Aguero|
|Bayern Munich sign Coman from Juventus for €35m|
|Cavani, Mbappe and Griezmann among nominees for UNFP awards|
|Roma stalwart De Rossi reflects on ´wrong´ career choices|
|Pep didn´t do his homework on English football, Grant claims|
|Verratti: I´d be angry if I played for Monaco|
|Sakho injury could be cruciate damage - Allardyce|
|Guardiola: I´m a better manager since joining Manchester City|
|Barcelona to report Malaga president to anti-violence commission after controversial Twitter post|
|Go fourth and prosper? Guardiola and Mourinho wrestling to lift Manchester horizons|
|Liverpool present new kit and crest to mark 125th anniversary|
|Manchester United captain Rooney vows to ´prove people wrong´ amid talk over future|
|Eto´o reveals Mourinho´s Champions League final masterstroke|
|Serbia well on the way to Russia 2018, but Stankovic highlights domestic difficulties|
|Mourinho unhappy with Smalling, Jones but insists defenders have Manchester United future|
|Pachuca 1 Tigres UANL 0 (2-1 agg): Alonso´s men win Champions League title|
|Copa Libertadores Review: Brawl erupts after Palmeiras beat Penarol|
|Madrid star Isco: This could be the best form of my career|
|Mascherano scores first Barcelona goal... in his 319th appearance|
|James: Five cup finals in LaLiga for Real Madrid|
|Zidane hails phenomenal Isco as Madrid stay level with Barca|
|Beating Bayern like this is ´madness´ - Tuchel|
|Moyes: Sunderland deserved something against Middlesbrough|
|Battle-scarred Arsenal star Sanchez takes to social media following last-gasp win|
|Sakho injury could bring end to Palace loan spell - Allardyce|
|Campbell expects extra ´spice´ in crucial north London derby|
|The challenge is to keep going - Pochettino delighted as Spurs hunt Chelsea|
|The target is clear - Wenger confident of Arsenal´s top four chances|