Hs7ep701_Sc53_AT-0026 The de facto Opening Night of the fall TV season was a juicy one. Rick Kissell of Variety wrote up the details that we’re still chewing on.

The five new series debuting Monday are grabbing most of the conversation, but one key story that isn’t getting a lot of initial play is the decline for “House” in its seventh-season premiere.

In this week’s weekly edition of Variety, I wrote about veteran mainstays facing potential vulnerabilities. The article focused on the 9 p.m. Thursday hour with “CSI,” “Grey’s Anatomy” and “The Office,” but “House” ended up being a perfect example of the issue.

Monday, “House” drew a 4.1 rating/11 share among viewers 18-49 and 10.5 million viewers overall, down nearly 40% from the 6.7/16, 17.1 million it earned for its season premiere a year ago.

It’s not entirely an apples-to-apples comparison; for one thing “House” had a two-hour premiere in 2009. And as with the Thursday veterans, it’s not as if there aren’t positive talking points, such as the Hugh Laurie starrer being the timeslot’s most-watched scripted program and No. 1 on broadcast in the hour among adults 18-34, scripted or otherwise.

However, the signs of weakness have significant implications, not the least of which was how they might have played into the disappointing launch of 9 p.m. drama “Lone Star.” By acclimation the best-reviewed new fall series and the subject of a near-ubiquitous marketing campaign, “Lone Star” got very little sampling: 1.3/3, 4.1 million. Fox has said it plans to show patience with the critically promising drama, but those are 2-year-old-finger-painting-on-the-walls numbers for the parent to deal with.

Know-it-alls like me felt that the “House” lead-in would help “Lone Star” in its battle with fellow freshman “The Event” (3.7/9, 11.2 million) on NBC. But I never expected that “The Event,” though it certainly was heavily marketed, would essentially match the audience for a perennial like “House” on its own. (“The Event” improved upon the 2.1/6 in 18-49 and 6.1 million overall viewers from 8 p.m. NBC entry “Chuck” by more than 75%.)

So instead of having a rock-solid Monday, Fox faces major questions — not only about whether “Lone Star” will last through the season (and to be clear, I’m rooting for it), but also about how much long-term life “House” has left. Hugh Laurie isn’t going away from Fox anytime soon, but this was a wakeup call.