The St. Louis Rams were without a key member of their defensive unit in Wednesday's practice, as Robert Quinn sat out with a concussion.

. . .had undergone knee surgery last spring. The biggest surprise on injury report was that DE Robert Quinn (concussion) did not practice.

— Jim Thomas (@jthom1) November 28, 2012

Quinn leads the team in sacks this season with 8.5 and is part of a pass rush duo with fellow defensive end Chris Long, who has seven sacks.

Heading into the year, St. Louis appeared to have two budding blue-chip players in Quinn and Long. In his first four seasons in the league, Long improved on his sack total every year and recorded 13 in 2011. In his rookie campaign last season, Quinn added five sacks in limited playing time.

Now, the tandem needs 4.5 sacks between them in the remaining five games to give the Rams two pass rushers with double-digit sacks.