West Ham United are furious with the FA after Stewart Downing turned out for England while injured.
The Mirror says West Ham are ready to sue the Football Association after Downing was allegedly played by England having had a painkilling injection in his knee.
The Upton Park club are understood to be in the "very early stages" of trying to ascertain the full chain of events.
The FA dispute the timing of the jab and maintain it was NOT given to the winger to get him through the first half of last Tuesday's game against Scotland.
A source said: "They have a duty of care towards our player."
England boss Roy Hodgson held talks with Hammers manager Sam Allardyce on the evening of the Scotland match, while the national team's medical team has also spoken with their West Ham counterparts.
The Irons' hierarchy are upset because Downing was unable to play for them against Everton on Saturday.
