CBS's Big Brother 6 premiered well on Thursday, handily winning its 8-9PM ET/PT time period in both total viewers and key demographics and teaming with CSI and Without A Trace repeats to lead CBS to a clean sweep in the night's primetime ratings.

According to the final national Nielsen ratings for July 7, Big Brother 6's premiere drew 8.47 million viewers, a 5.5/10 rating/share in households, a 3.4/11 rating/share in the Adults 18-49 demographic, a 3.1/11 rating/share in Adults 18-34, and a 4.0/12 rating/share in Adults 25-54 -- numbers that easily ranked the show first in its hour in all five of the ratings measurements.

While Big Brother 6's debut ratings were below those drawn by last summer's 90-minute premiere of Big Brother 5 ( 9.55 million viewers, 6.3/11 in households, 3.8/12 in Adults 18-49), Big Brother 6's one-hour premiere still easily outperformed CBS's previous Thursday 8-9PM ET/PT summer programming (its struggling The Cut reality series) and delivered the network's best delivery of the summer in Adults 18-34, Adults 18-49 and Adults 25-54.

Overall, CBS dominated the night's ratings, finishing first in households (7.9/14), total viewers (11.92 million), Adults 18-34 (3.0/10), Adults 18-49 (3.9/12) and Adults 25-54 (4.9/13).