Newcastle midfielder Yohan Cabaye is to undergo a scan on Tuesday in an effort to determine the severity of his groin injury.
The France international was forced off 37 minutes into the Magpies' 2-1 victory over Everton on Saturday.
He was clearly struggling as he left the field and fears have been raised as to his fitness heading forward.
Cabaye is due to link up with the French national side for friendlies against the United States and Belgium, but his participation in those fixtures has been cast into doubt.
Newcastle will be reluctant to release him if he is carrying a knock, with their summer signing from Lille having become a key figure at St James' Park.
The 25-year-old is, however, still waiting to discover if he will be sidelined for the foreseeable future.
He is not due to undergo medical tests until later in the week, at which point the situation will become clearer.
"I felt slight pain in my left adductor muscle," Cabaye told L'Equipe.
"I don't know how serious it is, but I will have a scan on Tuesday in Paris."