The Chilean was made aware of a number of sites and Twitter handles with popular Hammers account @ExWHUemployee a particular focus of The Times' report, which claimed the user had successfully announced 60 West Ham line-ups before they were made public.
The Times claimed Pellegrini’s pre-match routine since joining West Ham in the summer was to hold a meeting with the players four hours before kick-off, during which he names his side.
But The Times said elements of noteworthy team news have been appearing on match days before this point.
Pellegrini played everything with a straight bat when questioned in the wake of the initial report, telling reporters he wasn't unduly concerned about club leaks (The Sun).
Asked who was leaking the information, he added: "I don’t have any idea and I don’t worry about that. I worry about trying to win the three points.
"I don’t think it’s the most important thing. Maybe if you’re going to play against Chelsea, Watford or Liverpool, you are sure it will be the same starting XI as they played the last game and they play exactly the same way.
"I don’t hide too much about the starting XI."
But does the shock absence of West Ham's star man Marko Arnautovic for Saturday's heroic 1-1 draw at Leicester prove Pellegrini is getting on top of the situation?
Most Hammers fans were winded when they saw the teamsheets announced an hour before the late kick-off on Saturday and Arnautovic's name was not on it.
Many assumed an ongoing knee issue was to blame.
But it emerged that in fact the striker had been laid low by a sickness bug.
The Twitter ITK named in The Times report, @ExWHUEmployee revealed he had been informed.
But while Claude Puel's decision to drop Jamie Vardy - despite the striker declaring himself fit and ready after his own bout of illness - was plastered all over the press in the days leading up to the West Ham game, Arnautovic's absence took most by surprise.
If it means Pellegrini is getting to grips with just how much news makes it out of the dressing room onto social media and the sports press then that can only be a positive for West Ham.
Another positive is the fact Arnautovic should be fit to return to the side for Wednesday's massive Carabao Cup quarter-final tie against fierce rivals Tottenham.
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