Keegan told the clubs official website www.mcfc.co.uk: "It is more likely that he will be fit for Chelsea.
"We were impressed with the surgeon in Germany and without going into detail is was a minor operation which should clear up the niggling injury and should have him back in training soon.
"Hopefully the operation will put his mind at rest. The injury has been niggling him and he has not been himself.
"Eyal ninety per cent fit is still a good player but it is not the same force as Eyal a hundred per cent fit."