Collymore wrote in the People: "I know for sure from lads at Liverpool that he is one of the best coaches in the world.
"But he ran into problems at Anfield when he began to believe his own hype, when he stopped concentrating on what he was good at - coaching.
"After winning the Champions League he grew a goatee, started verbal jousting with Sir Alex Ferguson, and brought out stat sheets in press conferences.
"It was a game he was never going to win and in the end he lost his mojo because he was trying to run the club from top to bottom.
"This is an audition for him to see if he can become Chelsea's long-term manager - if such a thing still exists."