Gross-Matos suffered a knee injury in Friday's exhibition contest against Las Vegas, Jennifer Lee Chan of NBC Sports Bay Area reports.
The injury occurred in the first quarter when Gross-Matos' ankle got stuck as teammate De'Vondre Campbell tackled a ballcarrier. One play later, fellow defensive end Leonard Floyd suffered a knee injury of his own and also had to leave the game. Both players have been deemed questionable to return, though considering the exhibition nature of the contest, it wouldn't be surprising if neither plays another down Friday.