Liverpool manager Jurgen Klopp said he was close to phoning into a radio show when he heard criticism of Erik ten Hag.
Ten Hag has got off to a dismal start at Manchester United, who head into Monday's clash with rivals Liverpool on the back of two defeats in their opening games.
A 2-1 home defeat to Brighton and Hove Albion was followed by a humiliating 4-0 thrashing at the hands of Brentford last weekend.
But Klopp, whose team have hardly set the world alight in their two matches so far, drawing to both Fulham and Crystal Palace, said he has been angered by the harsh criticism of Ten Hag.
Using the example of talkSPORT pundit Gabriel Agbonlahor, Klopp suggested the reaction from some in the media has been overblown.
"It was obviously not nice for United after the Brentford game. We forget in these moments how good Brentford are, to be honest," he said in a press conference.
"I drove home and listened to talkSPORT and Gabby. He lost against us 6-0 my first year [Villa v Liverpool, Feb 2016], I couldn't remember him as a mentality monster on the pitch, but what he said about United on that show, I was close to calling in!
"I was close to calling in and telling him 'you have forgotten completely you used to be a player', it was unbelievable, and if ex-players are talking like this, you can imagine how everyone else is going.
"You then have to ask yourself 'how would you want to react in this situation?' You would of course fight back, that's completely normal and that's what we expect. The good news is when we play United it's always the same."
Klopp also believes Ten Hag, who oversaw a 4-0 win over Liverpool in pre-season, has a clear plan that he is attempting to implement.
"It's obvious what he wants to do, he wants to build out from the back. We played them in the pre-season [4-0 defeat in Bangkok], you could see and feel the high-press idea," Klopp added.
"We were for sure not ready for that game... we made some mistakes but they used them really well. The quality of United up front is ridiculous, I heard [Anthony] Martial can play probably, he played against us a really good game. Another boy with technique and speed.
"Football quality in midfield, who is it? [Christian] Eriksen, [Bruno] Fernandes, Donny van de Beek, Fred – Gabby doesn't like him I think but I think he's a really good player – and [Scott] McTominay so there's real quality there and it's just about how we deal with that, but again, these one, two games they played in the league, I saw them both and we have to try to figure out if he will change and if we will change and we go from there."
United might well have a new signing to debut against Liverpool, with the Red Devils closing in on a deal for Real Madrid midfielder Casemiro.