West Ham are believed to be considering lodging an official complaint over Fulham's team selection last weekend.
Fulham boss Roy Hodgson left out six regular first-team players for the game at West Ham's fellow Barclays Premier League relegation strugglers Hull on Saturday. Hull won 2-0, a result which leaves the Hammers outside the drop zone only on goal difference.
The Premier League have not yet received a complaint but West Ham are understood to be unhappy with Fulham, who were resting players ahead of their Europa League quarter-final tie against Wolfsburg.
The league has recent experience of such cases, having found Wolves guilty of fielding a weakened team earlier this season. The Molineux club were handed a £25,000 suspended fine after making 10 changes for a game at Manchester United in December.
Wolves manager Mick McCarthy has leapt to Hodgson's defence, even though a Hull revival could see his side dragged back into the relegation scrap.
McCarthy said: "I haven't got a problem with it. I am not bothered what team they played.
"It is just something that the high and mighty, who tend to look at their own teams, don't like when it is happening.
"It is about making the most of your squad and utilising your squad to the best of their abilities. That is what I did and that is what Roy did.
"Fulham are still in Europe, so good luck to them. They are probably safe with the points they have got and don't forget we have still got them to play this season.
"But good luck to Roy and if it means he wins that Europa League then I will be thrilled for him. He has had a great season. If they have still got anything to play for when they play us and want to play a weakened team against me, I will be delighted."
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