Jordan Schultz of BleacherReport.com reports that team officials fear that Phillips sustained a torn quadriceps during Sunday's 26-25 loss to the Rams.
Phillips was carted off the field after aggravating what was initially reported as a knee injury. Schultz notes that Phillips -- who has started all nine games for the Giants since being signed off the Eagles' practice squad Oct. 20 -- will have an MRI on Monday to confirm the injury and that surgery is a possibility.