It is hard to argue that anyone is more important to this Everton side than James McCarthy after looking at their record when he is not available.
McCarthy was brought to Goodison Park in Roberto Martinez's first summer in charge and he has repaid the faith that the Spaniard showed in him already.
The Republic of Ireland international's exuberance in midfield has proved to be a vital component of Everton's game and in his absence his importance is showing even more.
Everton have won just two games out of the 21 he has missed since he arrived on Merseyside - with those victories coming against Fulham and Queens Park Rangers.
It is a startling statistic, which shows just how valuable he has become to the Toffees' progress.
With the side struggling so badly, Martinez would, therefore, have hoped to have McCarthy available to him, but his injury has come at the worst possible time.
The 24-year-old has been on the treatment table since December and his return to action simply cannot come soon enough, as the side look to break out of what has been a prolonged slump.
If they do not, McCarthy's future, more worryingly, may be in doubt because Everton's struggles could attract clubs to their key men.
Tottenham Hotspur's interest in the all-action central-midfielder has been reported by the Daily Mirror and Everton will be determined to keep hold of him.
According to the report, at the moment Spurs are said to be willing to pay around £25 million for McCarthy, but it is hard to place a monetary value on him given how integral he is to the Toffees' results.