Phillips, 34, will go under the knife on Monday to remove a small growth which is causing him discomfort and the player-coach expects to be back in action by the end of September.
An ever-present for Alex as they secured promotion from npower League Two last season, Phillips has been warned by boss Steve Davis that he is not guaranteed to dislodge deputy Alan Martin when back in the frame.
Martin has taken the gloves over pre-season and made his senior debut for the Railwaymen in Saturday's thumping 5-0 Capital One Cup win over Hartlepool at Gresty Road.
"Even if he didn't have the operation Steve would be out for a similar length of time, so it made sense to get rid of the discomfort once and for all," Davis told The Sentinel.
"Alan has been playing very well and we have been pleased with him."