The Chelsea man is struggling with a knee injury he picked up during January's African Cup of Nations in Angola, where his side finished runners up to champions Egypt.

He was included in Ghana's preliminary squad for the 11 June-11 July World Cup finals in South Africa but his participation in the anticipated tournament remains in doubt.

"I have to keep working hard to be fit. Once I am fit I hope to feature in at least one trial match before the World Cup starts," Essien said on Wednesday.

"I haven't played since January so I will need games before the real thing starts.

"However even if I don't get any trial games, as long I am declared fit by the medical team then I will be in South Africa for sure."

Essien's presence in Ghana's midfield was sorely missed during the Nations Cup although the Black Stars managed to reach the final before losing 1-0 to Egypt.

He is one of the few experienced players in Ghana's young squad.

"At the moment I am carrying on with my rehabilitation programme. Chelsea have allowed me to carry on until the end of May at Cobham and my fitness will be assessed by the experts as the days go by," Essien added.

"I feel a lot better than I did a few weeks ago so I am keeping my fingers crossed that all will be well."

Ghana, who play in Group D, open their World Cup campaign against Serbia on June 13.

They will also face three-time world champions Germany and Australia in the group.