Everton boss David Moyes believes it could take Yakubu up to four months to find his top goalscoring form.
The Nigerian striker has only managed to score in the League Cup win at Hull since returning to action at the end of August after rupturing his Achilles 11 months ago.
The 26-year-old has yet to start a Premier League game, but with the Toffees about to enter a gruelling seven-game spell in 23 days, the former Middlesbrough and Portsmouth marksman can expect some game time.
But Moyes has warned the Goodison faithful not too expect too much of their powerful forward.
He said: "If you look at people who have ruptured their Achilles, it can take the same time again - even though you are 'fit' - to get back into the way of playing.
"It was a really bad injury and could have been career-threatening.
"We'd like to get Yak up to the level but we don't think he is quite there yet. It's likely to take time rather than anything else.
"Because he has missed a year's football, we want to get him sharp and right.
"We don't know if that will take a week or if it will take three or four months yet."
Everton are bidding to continue their six-match unbeaten run when Wolves visit Merseyside on Saturday.
But they must continue without the likes of skipper Phil Neville, Mikel Arteta and Phil Jagielka, and Moyes has told the available playing staff that it is up to them to do the business on the pitch.
He added: "We will not get any injured players back this month. We won't have Jagielka, Arteta, Neville or Victor Anichebe, that's for sure."