Alex Ferguson hit back on Friday at comments by former Manchester United midfielder Owen Hargreaves, who accused the club's staff of mishandling his long-running knee problems.
Hargreaves, who made a goal-scoring debut for Manchester City in Wednesday's League Cup victory over Birmingham, suggested after the game his fitness problems at United may have been exacerbated by treatment he received.
United are expected to release a statement after consultations with club lawyers and the medics implicated in Hargreaves' comments but veteran manager Ferguson clearly felt compelled to defend the reputations of his employees.
"We've been trying to analyse all the stuff he's said this morning," said Ferguson at his weekly Friday press briefing. "We will have a club statement this afternoon to address that.
"As far as I'm concerned, all it's worth is this: my medical staff is one of the main reasons Manchester United have been so successful the last few years, there is no doubt at all about that.
"I have a fantastic medical staff, great sports science (staff). Do you think we would have been so successful the last few years if we didn't have an operation at 100 per cent? They are brilliant. The doctor, his five physiotherapists, the sports scientists, all fantastic.
"That is my opinion of Manchester United and that is more important than what anyone else has got to say about it."
Hargreaves, who underwent two knee operations, played just six minutes of first-team football for United from September 2008 until his departure from Old Trafford when they declined to offer him a new contract this summer.
Speaking after his successful comeback this week, Hargreaves told reporters: "I received some injections but my tendon was never the same. After the injections, I tried to get back on my feet and they said my tendon was good, but it felt like I was made out of glass. That obviously had a huge impact."
Hargreaves also claimed he was "left to pick up the pieces" by his former employers and added: "With my tendon injury, I've had to be a guinea pig for a lot of these treatments."
With relations between the two Manchester clubs strained, to say the least, the latest bone of contention - and Ferguson's clear anger at Hargreaves' accusations - is merely going to add to the growing rivalry.
Meanwhile, Ferguson also revealed that another rivalry involving his club had far more sinister overtones in midweek after United's League Cup victory at Leeds was overshadowed by unsavoury crowd disturbances.
West Yorkshire Police are still conducting investigations, not least into tasteless chanting between rival supporters that referenced the Munich air disaster and the deaths of Leeds United supporters in Turkey in 2000.
"Historically, it has been there for a long time," said Ferguson of the tension between Manchester and Leeds United.
"Liverpool and Manchester United has always been fierce in many aspects and sometimes supporters can be a bad part of that. But it has never reached the levels of Leeds.
"It was frightening. There were seven police vans outside the hotel to protect the team. I don't know why it is. I don't understand it, to be honest with you. But it is there and it is not nice."