NFL Network insider Jason La Canfora reports, via a league source, that the initial concern with Weaver is a season-ending ACL tear, but there is no official diagnosis and more testing has to be done.
Weaver was injured on a rushing play early in the second quarter. His knee was severely twisted on a direct hit and he was down for several minutes. Coach Andy Reid came to Weaver's side. Weaver was helped off the field by teammates and the training staff.
Also injured for the Eagles was starting center Jamaal Jackson, who will not return after suffering an elbow injury in the second quarter.
Jackson tore a left knee ligament at the end of last season.
The Associated Press contributed to this report.