Roberto Martinez has told the Guardian that Tom Cleverley is already playing a massive role at Everton.
Cleverley was a summer recruit for the Toffees, after he was made available on a free transfer - following the expiration of his contract at Manchester United.
The England international has made a big impression at Goodison Park, but injury problems have plagued his time at the club.
Cleverley made a bright start to his Everton career, before injury struck at the end of August.
The 26-year-old has only just come back into contention, and he came off the bench for Everton in their 4-3 defeat against Stoke City at the weekend, but he picked up another knock during the contest.
And Martinez said: “Tom felt his achilles tendon and we will have to assess it.
“He tried to stay on as long as he could. He played the pass for Romelu Lukaku for the second goal but he had to come off. He made a really big impact when he came on and he was playing a massive role.”
Cleverley went into the match against Stoke having just netted his first Everton goal to secure their victory against Newcastle United.
His energy and dynamism has caught the eye, but his absence will be a blow for the side - especially as James McCarthy was also forced off with injury against Stoke.
Everton are currently in 11th place in the Premier League table, with their next match coming against Tottenham Hotspur on Sunday.