Nielsen overnights for Wednesday night reflect what has been the pattern since the Olympics opened: huge ratings for NBC, with not much to shout about on the other broadcast networks.

The London Olympics continue to pace ahead of the Beijing Games four years ago, reportedly up 7% in viewers 18-49 and up 13% in total viewers through the first six nights, including the opening ceremony.

Among the casualties last night: CBS’s “Big Brother” hit a season low with a 1.9 average rating in the key 18-49 demo, off one-tenth from a week earlier, TVbytheNumbers.com reports.

Other than that, CBS didn’t really try, putting up reruns of “Criminal Minds” and “CSI.”

ABC gave it a go at 10 p.m. with a fresh episode of “Final Witness,” which managed only a 0.8 in 18-49, down two-tenths from last week.

ABC filled out its prime-time schedule with repeats of “The Middle,” “Suburgatory” and “Modern Family,” while Fox put up a two-hour repeat of “So You Think You Can Dance.”

For prime time overall, it was NBC way out front with a 9.7 average rating in the 18-49 demo; the closest anyone else came was Univision with a 1.4 average, followed by CBS (1.3), ABC (0.8) and Fox (0.7). In total viewers, NBC averaged 30.6 million, followed by CBS with 4.6 million, Univision with 3.6 million, ABC with 2.8 million and Fox with 2.1 million.