Tottenham manager Mauricio Pochettino said Manchester United counterpart Jose Mourinho put Eric Dier in a compromising position after attempting to lure him to Old Trafford.
England international Dier, 23, was linked with a move to Premier League giants United in the off-season before Mourinho opted for Nemanja Matic from Chelsea.
Dier – under contract until 2021 having signed a new contract in September last year – was weighing up interest from United in an effort to play more regularly in midfield following the arrival of Victor Wanyama at Tottenham.
Pochettino revealed he was angered by Dier, who is also accustomed to defence, and Mourinho after watching the pair chat and laugh following Tottenham's 1-0 loss to United at Old Trafford last December.
"I've told Eric he has what it takes to be the best English centre back but he has to be convinced of that himself. We've put the conditions in place for him to improve. But he broke into the national team thanks to his displays in the [midfield] holding role and ended up scoring a couple of big goals," Pochettino said in an extract from the new book 'Brave New World' published by the Daily Mail.
"After we signed [Victor] Wanyama [in summer, 2016], Eric, who now sees himself as a midfielder, felt that we had treated him badly because Wanyama's arrival would halt his development. His performances have started to suffer this season. We've spoken a lot recently but I've felt he hasn't been telling me everything. Later on, I once again tried to understand why he couldn't shake off the shackles and I offered to help him with whatever it was.
"Nothing. Then I found out that United have made an approach and the player is being destabilised. His people have been putting pressure on him, although United are not promising anything.
"Mourinho and I had finished our interviews at Old Trafford [after the 1-0 defeat by Manchester United, December 2016] and the players were doing their warm-down on the pitch. When Jose was done with the press, he stood by the entrance to the tunnel and regarded the returning players.
"He greeted Moussa Sissoko and hugged Dier. They passed by me en route to the dressing rooms, laughing, speaking in Portuguese. Maybe it is a common Mourinho tactic, but he put Eric in a compromising position. You cannot do that after a defeat.
"'Are you friends with Mourinho?' I asked him. 'No, but I've known him a long time, from my time in Portugal... one of his godsons coached me. He always says hello.'
"I sat down with Eric after lunch on Monday and we chatted for four hours about the whole shebang: his agent, family, confusion.
"As for the Mourinho incident, 'What could I have done?' Eric asked me. He told me about United's interest since last summer  and I explained the situation to him clearly.
"'Look, you aren't leaving because you signed a five-year deal with us in August. You're among the highest-paid players at Tottenham at the age of 22. You're important to us and you could become the best centre back in the Premier League.'
"Ever since that conversation, Eric admits that he could have waited for Mourinho to be out of sight before heading to the dressing room."
|Hector pledges future to struggling Cologne|
|´Crazy´ fans can help Roma knock out Liverpool, says Voller|
|Sharapova not short on desire despite struggles|
|South Africa to test unbeaten home record vs Pakistan & Sri Lanka|
|Kerr: Ginobili should keep playing another two years|
|He keeps getting better and better - Henderson full of praise for PFA winner Salah|
|Roma v Liverpool: Giallorossi have chance to write positive headlines|
|Prove you are the best - Povetkin promoter lays down Joshua gauntlet|
|Wenger will not be short of offers from clubs - Dein|
|LeBron hails Korver & Clarkson as Cavs square series|
|I may play the kids in the FA Cup next season, reveals bemused Pochettino|
|Simeone weighing up three-man defence for Arsenal tie|
|Kings wait for Bogut signing approval|
|Vieira refuses to address Arsenal rumours and Wenger departure|
|Cueto lowers historic ERA in Giants´ win|
|Spurs avoid sweep, Cavs edge Pacers|
|WATCH: Smith beats first-quarter buzzer with near full-court shot|
|Harden, D´Antoni hope Rockets regain top form|
|Man United star Pogba can win Ballon d´Or, says Ronaldinho|
|Silva loves me more than his girlfriend – Mendy|
|MLS Review: Timbers end NYC´s unbeaten start, Sounders claim first win|
|Flyers´ Couturier played with torn MCL|
|Emery praises PSG for maintaining motivation|
|Cavs´ Hill out for game four with back spasms|
|Oblak unsure over Atletico Madrid future|
|Klopp ready for ´different´ Roma test|
|Salah always determined to prove his Premier League worth|
|Landry earns first PGA Tour victory at Texas Open|
|City´s Sane named PFA Young Player of the Year|
|Salah pips De Bruyne to PFA Players´ Player of the Year award|
|Napoli bus spat at and insulted, Sarri claims|
|Navas will be at Real Madrid for many years – Perez|
|Juve still have the advantage, Allegri claims|
|Racing coach Labit ready for ´formidable´ Leinster challenge|
|Smalling not giving up on World Cup|
|Hard to catch Man City if they invest, Mourinho warns|
|Pogba: I have no problem with Mourinho|
|Koulibaly: Napoli have always believed in Scudetto|
|Bordeaux 0 Paris Saint-Germain 1: Lo Celso keeps champions on track for records|
|Atletico Madrid 0 Real Betis 0: More concerns for Simeone ahead of Europa League|
|Juventus 0 Napoli 1: Partenopei close the gap thanks to Koulibaly|
|Dominant Marquez maintains perfect record in Austin|
|Guardiola has no problem with Manchester City pitch invasion|
|Neymar must join Real Madrid to become the best - Rivaldo|
|There was no player better than De Bruyne - Guardiola backs City man for PFA award|
|Top managers should want Arsenal job, says Moyes|
|Manchester City boss Guardiola aiming to smash records following title triumph|
|Las Palmas relegated from LaLiga after 4-0 home defeat to Alaves|
|Archer and Gowtham combine for dramatic Royals victory|
|This won´t happen forever - dominant Nadal reflects on latest success|
|Andrew Bogut returns to Australia, signs with Sydney Kings|
|Manchester City break Premier League passing and possession records|
|Conte: Morata still important despite Giroud impact|
|Inter gave up against Chievo, admits Spalletti|
|Conte denies Mourinho rift ahead of FA Cup final|
|Levy claims fifth European Tour crown in Rabat|
|Diouf miss ´a turning point´ for both Stoke and Burnley|
|Hughes upset with lack of VAR after Southampton´s FA Cup loss|
|Manchester City 5 Swansea City 0: Guardiola´s champions turn on the style|
|Manchester United are FA Cup favourites, claims Chelsea boss Conte|
|United States and Czech Republic reach Fed Cup final|
|Rapid start sees Racing through to Champions Cup final|
|Benevento relegated after late Crotone winner|
|Jungels roars to Liege-Bastogne-Liege victory|
|I don´t need to die anymore - Wenger reflects on Arsenal ´funeral´|
|Hazard gives Conte a dazzling reminder of better days|
|Playing at Wembley is like playing in my garden - Giroud|
|Sevilla president casts doubt on future of Montella|
|´Hurtful´ fans damaged Arsenal´s image, Wenger claims|
|Chelsea 2 Southampton 0: Giroud and Morata book FA Cup final spot|