Both players were listed as questionable. Alonso "tweaked" his knee in Friday's practice, which put his status for the game in doubt.
Alonso, the Bills' second-round draft pick, has played every defensive snap this season. Meanwhile, Urbik has started all 13 games at right guard.
Here's the full list of Bills inactives:
QB Jeff Tuel
RB Ronnie Wingo
OL Mark Asper
TE Tony Moeaki