Everton defender Joseph Yobo has been ruled out for four weeks with a hamstring injury.
The 29-year-old Nigeria international initially suffered the injury in the Merseyside derby defeat to Liverpool on November 29, but aggravated the problem last weekend in the 2-2 draw with Tottenham.
Yobo will miss Saturday's clash with Chelsea as the Toffees seek to end a run of four Barclays Premier League fixtures without a win.
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