The Aussie manager is under intense pressure at Spurs having lost 16 of his 30 Premier League matches so far this season, with the London club on course to finish outside the top 10 for the first time since 2008.
Speaking on TNT Sports’ YouTube channel ahead of Tottenham’s Europa League quarter-final first-leg with Eintracht Frankfurt on Thursday night, Hart discussed working under Ange at Celtic alongside fellow pundits Rio Ferdinand, Joe Cole, Joleon Lescott, Owen Hargreaves, Steve McManaman and presenter Reshmin Chowdhury.
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The 37-year-old former Hoops keeper said: “I loved him, but I was in a successful team, playing, you know, some football that I'd never played in my career.”
Asked whether the Ange he’s seeing in post-match interviews now is totally different to the one he played under, Hart responded:
“To an extent, but he was always engaging in terms of, he'd answer the question, but he'd answer it his way.
“Even him having a conversation with a fan about being respectful, that's kind of who he is. If he saw something happen in the street that he didn't think was right, he'd say something.
“But just the Tottenham team, the constant losses, it's bringing that side out of him more.
“But it was there when we were at Celtic. If we lost the odd game or we were questioned the way he played, especially in Europe. We went to Real Madrid and went toe-to-toe with them. And we did all right at home, but we got pumped five-nil away.
“But he stood by it and he would stand by anyone who called him out. Twenty-man press conference, if one man was whispering about him over there, he'd be like, what you saying? What have you got to say? Say it to me.
“But at Tottenham it's difficult because he's constantly having to deal with it.”