According to KCNC-DT CBS 4 in Denver...
NFL Football
Broncos at Rams
(HD)
and WJZ-DT CBS 13 in Baltimore...
NFL Football
Ravens at Buccaneers
So it should be Broncos Rams, Chiefs Bengals, and Bills Patriots as the 3 CBS broadcasts in HD this sunday.
According to CBS's own schedule: http://sportsline.com/cbssports/schedules/page/nfl
It's the Broncos-Rams game that should be in HD (please please, huge Broncos fan here that just wants to see all the games in HD please please!).