But the 27-year-old's rehab is progressing well and he now could be back in club colours when the Ospreys face Connacht in the Magners League on February 21.
"If Mike continues his current progress with no hiccups or setbacks over the coming weeks, then he has a realistic chance of being available for game time in mid-February," said Ospreys physio Chris Towers.
"Mike is now 12 weeks post-op following repair of ankle ligaments he damaged in October. He is now entering a phase of progressive functional rehab with a return to play in mind.
"Over the last four weeks since coming out of plaster he has undertaken an intensive rehabilitation and treatment programme which we've been running in conjunction with the WRU medical team, and we're all satisfied that clinically he couldn't be any better at this stage of his recovery."
The former Scarlets and Blues No9 has not been included in Warren Gatland's 35-man squad but it would not be a massive surprise if calls were made for him to be added to the party for the latter stages of the competition.
However, the Ospreys themselves insist Phillips' will neither be rushed into anything nor thrown in at the deep end, for either club nor country.
"Looking at the fixture list, we are targeting the Connacht fixture for his return," added Towers.
"However, as with any of our players returning from long-term injury or following surgery, we will be looking to limit his game time initially, gradually building this up over a number of weeks, as this initial return to play period remains an important, ongoing part of his recovery to full health and fitness in terms of his ankle."