The injury occurred in the first quarter of Minnesota's 35-24 win over Middle Tennessee State on Saturday.
Ekpe and Poock were starters. Rallis had played in both of Minnesota's first two games this season.
"Tough thing is he worked so hard and has really, really played well," coach Jerry Kill said.
Rallis is the younger brother of former Gophers captain Mike Rallis.
- Molly Geary