However, scans have revealed no serious damage and the 34-year-old hitman has been given the green light to resume training next week.
Phillips could now be fit for Albion's next match - a trip to Colchester United on October 20.
"Kevin underwent a precautionary scan yesterday which confirmed the club's initial diagnosis that there is no serious problem with his ankle," confirmed a club statement.
However, the Baggies are waiting to discover the extent of a shoulder injury suffered by Carl Hoefkens which forced the defender to pull out of the Belgium squad for their Euro 2008 qualifiers with Finland and Armenia.