The winger had only just returned from a seven-week lay-off with an ankle injury before picking up another problem.
But his knock is not a recurrence of that ankle injury and Baggies boss Darren Moore is expecting him back for training this week ahead of Saturday's home match against bottom club Ipswich,
"Matty Phillips has just come back and when you're out for a little while you pick up little knocks and strains," explained Moore.
"It's not a recurrence of the ankle injury, which is pleasing to say. He’ll be back in training this week.”
Phillips has been involved in 11 goals in 24 Championship appearances this season and the former QPR man has been sorely missed in recent weeks.
The Baggies have only won three of the seven league games he's been out for, and his injury coincided with Harvey Barnes's return to parent club Leicester City, removing Albion's outlets of pace.
Left-back Kieran Gibbs also missed last Friday's match at Elland Road with a hip problem.
Although Moore described it as a 'slight' injury, the time-frame of his return is less sure.
Gibbs has been first-choice left-back for the whole of the season, but missed two games in October and November with a hip injury picked up against Derby.
Meanwhile, Luton Town are reportedly preparing another approach for Albion assistant head coach Graeme Jones in the summer.
The Hatters wanted Jones to replace Nathan Jones after he left for Stoke, but Darren Moore's No.2 turned them down.
Mick Harford is in caretaker charge at Luton, who are five points clear at the top of League One, until the end of the season.
But he does not want the job on a permanent basis and Luton are on the hunt for a manager.