|Essien has been out since the Africa Cup of Nations in January [GALLO/GETTY]
Michael Essien may miss the World Cup because of his long-term knee injury.
The Ghana and Chelsea has been sidelined since his country reached the Africa Cup of Nations final in Angola in January and recent complications have stalled his recovery.
"If I can make it in time for the World Cup then great but if not I still have my whole career ahead of me and that is more important than anything," he told the English Premier League club's website.
"The last thing I want to do is rush back too soon and cause further problems down the line."
Ghana will face Germany, Australia and Serbia in World Cup Group D in South Africa in June.
Essien said the stumbling block now was bruising, rather than the meniscus tear he suffered during the Nations Cup.
"I started doing a little bit of running recently which was a big step forward but that led to some pain," he said on Saturday.
"A scan showed I had some bruising so I had to stop running and I am now taking it easy until the bruising dies down.
"Unfortunately I don't think I will be making a repeat of last season and may not be returning for the last few league games and the FA Cup final."