Kevin Mirallas will miss the remaining three games of the season.
The Everton forward limped off at the very end of Sunday's win over Manchester United, after scoring the Blues' second goal shortly before half time.
And Roberto Martinez today revealed that the Belgian has a small tear in his groin and will be sidelined for matches against Southampton this weekend, the visit of Manchester City on 3 May and the last game of the season at Hull City.
Martinez also revealed that Sylvain Distin is a doubt for Saturday’s trip to Southampton.
Martinez told evertontv: “Kevin's scans came back and they have revealed a small tear in his groin. He is going to be out for the season which is a real disappointment and a shame because he was in a phenomenal moment of form.
“But the memory we have of his performance against Manchester United is a terrific image. The way he took his goal and how he was a dynamic force throughout the game – it was an outstanding performance.
“It’s a great way to finish the season if it’s the last game he is going to be involved in this campaign.”
Martinez, however, moved to quash any fears that Mirallas’ groin problem would put the winger’s World Cup involvement in jeopardy.
The Spaniard added: “It is not a major injury. It could be anything up to five or six weeks, and that’s looking at the worst-case scenario. Kevin is a quick healer and I would be surprised if he is not available after three or four weeks.
“It’s a shame because we had three really important games and Kevin has always been really influential this campaign. But the most important aspect now is that we get him fully fit and ready to participate with Belgium in the World Cup.”
Distin was also forced off in the weekend victory over Manchester United.
Martinez revealed that the next 48 hours would determine the severity of the Frenchman’s hamstring injury, though he accepts the centre-half is a big doubt for the weekend trip to St Mary’s.
“It’s very much doubtful,” Martinez said when asked about Distin’s chances of being fit for the Southampton game.
“The scans revealed something of a problem but until the swelling clears it is impossible make the right diagnosis. In the next 48 hours we will find out how long Sylvain is going to be out.”