The 31-year old Malian midfielder was originally set to miss up to six months after having surgery on a knee injury but the new prognosis is much better for the Cottagers according to manager Martin Jol.
"Diarra had a minor operation but he will still be out for the next four weeks at least. They removed a few little pieces of bone from his knee and that was it so that was pleasing. There was not a lot of damage," said the Dutchman.
"If there had been more damage with his knee with his ligaments or his cruciate then he could have been out for a lot longer but it was exactly what we thought it was. But it's still four weeks."