Brendan Rodgers has taken Sir Alex Ferguson to task over his comments about Liverpool midfielder Jordan Henderson.
Sir Alex Ferguson criticised Henderson's running style in his recently released autobiography. The ex-United boss said his upright gait "might cause him problems later in his career."
But Rodgers felt the words were excessively harsh.
In response to the remarks, Rodgers said: "I have got to be honest, that surprised me about Jordan, coming from someone with that status in the game; someone who has worked with young players and understands the impact words can have on them.
"I have to say I thought it was inappropriate. It's not something that is coming from factual credence.
"This is a boy who can play two or three games on the spin, one after the other. He is a wonderful athlete. One thing I would say is that, physically, he is an absolute machine.
"Jordan is a great kid, a real honest boy who will work and fight to be the best he can be.
"I’m sure if Sir Alex bumps into Jordan, he will apologise. Sir Alex hasn’t worked with him, so doesn’t know what type of player he is. I know he is improving all the time."
Henderson, a £17m signing from Sunderland, is beginning to settle in at Anfield after a difficult transition from Wearside.
The 23-year-old was by no means the only Liverpool employee singled out by Ferguson in his new book, with special mentions also reserved for Steven Gerard and Rodgers.
And the United boss said the Reds need up to eight new players if they're to mount a title challenge this season, despite their strong start to the new campaign.
Liverpool face West Brom at Anfield this weekend, while United welcome Stoke City to Old Trafford on Saturday afternoon.