Everton manager Roberto Martinez admits he may have to take a closer a look at James McCarthy's workload to solve the midfielder's fitness issues.
The 24-year-old was sent home by the Republic of Ireland last week after complaining of a hamstring problem and is a doubt for Saturday's visit of West Ham.
It is the latest in a series of niggles McCarthy has had this season and Martinez is keen to find the source of the issue,
"We need to assess it. Maybe it's managing the work he does in training," Martinez told the Liverpool Echo.
"We need to find the right formula because we need to make sure we don't get these sort of injuries on a regular basis.
"James has played a huge amount of games and is still a very young man.
"He's a super fit boy and he shouldn't be picking up these sort of knocks.
"He's had this same injury before but not in the same leg.
"It's partly normal phases of development and growing into the physical demands of your role."
Republic assistant manager Roy Keane claimed the Toffees overstate injuries when McCarthy and team-mate Seamus Coleman are sent on international duty, saying: "You always get the impression from Everton that Seamus and James are both barely able to walk."
But Martinez rejected that accusation.
"James was desperate to be involved with his national team but he couldn't make it," he added.