RAYMOND VERHEIJEN is well-known for criticising managers for their training techniques - with Liverpool boss Jurgen Klopp his latest victim.
Verheijen claimed on Twitter last week that Klopp's Liverpool would suffer because of his playing style having previously blamed Arsene Wenger for Arsenal's injury problems.
Who is Raymond Verheijen?
Verheijen, 44, was a promising academy player but was forced to retire through injury at the age of 18 and took up coaching while still a teenager.
He studied exercise physiology and sports psychology at university in Amsterdam as well as studying for a masters at John Moores University in Liverpool.
He published a book on the back of his studies called Conditioning for Soccer which was adopted by the Dutch FA as part of their coaching education.
Specialising in fitness coaching, Verheijen subsequently became an instructor of coaches and Ruud Gullit, Ronald Koeman and Frank Rijkaard were some of his first students.
He also worked as an assistant on the Dutch coaching staff at Euro 2000 and attended every World Cup and Euros for the next 15 years working as a coach with the Netherlands, South Korea, Russia and the Argentina team which reached the World Cup final in 2014.
Verheijen has been used as a consultant on player conditioning by Barcelona, Chelsea, Manchester City and Rangers and in 2011 was appointed assistant manager of Wales by Gary Speed, a role he occupied until the manager's tragic death.
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The Dutchman now works as a consultant for a number of national governing bodies.
What has Verheijen said about Jurgen Klopp?
Verheijen believes Klopp's high-energy pressing style will come back to haunt him as the season goes on.
"Because of Klopp's intense training & playing style, it's very likely the Liverpool players will struggle in the last months of this season," Verheijen said.
The Liverpool boss responded by complaining about the winter fixture pile-up and Verheijen's comments.
"Now I have seen the fixtures and I am not too happy," said Klopp.
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"We have less than 48 hours between our game against Man City on December 31 and in Sunderland on January 2.
"How does this work? And then you will sit there and say 'You didn't perform too well, how did this happen?' or 'Injuries. Oh?' and then this Dutch guy says 'The training is not too good'.
"How do you prepare a team for this. Do you say 'Only 50 per cent against City because we have Sunderland on Monday'."
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The Dutchman was quick to respond with another swipe.
"Liverpool manager Klopp caused 20 hamstring injuries in 10 months but keeps blaming external factors for injuries," Verheijen said.
What has Verheijen said about Arsene Wenger?
Verheijen has repeatedly criticised Wenger over Arsenal's recent poor record with injury.
The French manager appears to have been extremely unlucky with players such as Aaron Ramsey, Jack Wilshere, Alex Oxlade-Chamberlain and Theo Walcott all struggling to maintain fitness levels for any extended period of time.
But Verheijen believes Wenger himself, and not luck, is to blame.
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"The main reason for injures in football is accumulation of fatigue because when you accumulate fatigue over time your brain has less control over your body and your coordination goes down and then you are vulnerable to injuries," he said in 2015.
“The question is: who is the main reason for fatigue?
"The main reason for the fatigue is the fitness football coach because he is responsible for the planning of training.
"Arsene Wenger is responsible for fatigue and injuries and the medical staff can only cure the problem.”
A year later, Verheijen revisited the problem.
"Last year there was a big investigation and all the stats were checked and for the last 13 seasons Arsenal have an injury, on average, once every five games and that’s unprecedented," he said this summer.
"It is a responsibility of Arsene Wenger to sort this problem, but he hasn’t fixed it for 13 years.”