Chelsea midfielder Michael Essien has handed manager Luiz Felipe Scolari an injury headache.

Essien limped out of Ghana's World Cup qualifier against Libya early in the first half as the Black Stars slumped to a 1-0 defeat.

Reports suggest the 25-year-old could be sidelined for up to four weeks with the problem, and would therefore miss the Blues' crucial Premier League clash with Manchester United on September 21.

Chelsea medical staff are set to look at the injury this week ahead of the weekend's trip to Manchester City, and Essien is hopeful of making a swift recovery.

He told skysports.com: "My injury? It is serious but I can be ready again soon."