Viva Don’t bet the house on “Viva Laughlin” just yet.

The Thursday night preview of “Laughlin” averaged just a 2.3 rating and 6 share among adults 18-49 — quite a steep drop-off (-65%) from its “CSI” lead-in (6.5/15). That sound you heard at 10 p.m. last night was scores of “CSI” viewers stumbling over the ottoman while frantically hunting for the remote.

In comparison, the season bow of “Without a Trace” in the 10 p.m. slot a few weeks ago pulled a strong 4.7/13 in the demo. And last year, “Shark” swam into the post-“CSI” spot with a 4.1/11.

News wasn’t all bad for “Laughlin,” which managed to place second in the hour (in front of “Big Shots”) among total viewers (8.4 million, vs. 7.6 million).

But it’s still not a good sign for the Hugh Jackman-produced hour, which is based on the hit BBC format “Viva Blackpool.” “Laughlin” moves to Sunday this weekend — and if it doesn’t perform there, “The Amazing Race” is always waiting in the wings.

Critics weren’t too kind on “Laughlin,” but the show also wasn’t helped by its marketing campaign. Promos appeared to strenuously avoid any overt depiction of the show’s central gimmick: Characters singing along (and sometimes dancing) to well-known pop hits. Had those scenes been more widely promoted, perhaps there would have been more of a curiosity factor, and as a result, bigger tune-in.

Nonetheless, at least props to CBS for taking a gamble on “Viva,” even if that wager ultimately didn’t pay off.

— Michael Schneider