"Chuck" has certainly seen better days.

The NBC series some thought might help the network save its Monday nights hit a season low this week, earning a 3.5 rating/6 share, according to Fast National ratings from The Nielsen Co. That matched the Zachary Levi series previous low of a 3.5/5 achieved twice in March 2009 before bouncing back slightly through its final episodes in April.

Monday's viewership was down more than 10 percent off its 3.9/6 average, and is more than 18 percent off its season premiere Jan. 11. "Chuck" this season, however, is just slightly behind its 4.0/6 average in the 2008-09 season, but is nearly 19 percent off the pace it set in its freshman year.

This week's episode finished well behind "House," which picked up a 6.7/11, and behind the comedy block from CBS which included a rerun of "How I Met Your Mother," but a new episode of "Rules of Engagement." That show fell more than 25 percent from its previous week to a 4.7/8.

"Lost" is struggling to keep viewers as well. The ABC series Tuesday earned a 5.1/8. It's down nearly 9 percent from the audience it was generating the last two weeks, and off more than 26 percent from its premiere.

It's averaging a 6.0/9 after eight episodes, 22 percent off the 2007-08 season, but still more than 3 percent ahead of how the show did last season. The eighth episode of "Lost" last season earned a 6.3/10, and was averaging a 6.3/10 by that point. However, later episodes last season would slip into the mid-5.0 household range, bringing its overall season numbers down.

Fast Nationals usually provide a snapshot of what Americans are watching by pulling numbers from the top urban markets that includes both live viewing and same-day timeshifted viewing. A rating point generally represents more than 1.1 million households while the share indicates the percentage of televisions turned on that was tuned to the specific program. These numbers typically shift when final ratings are issued.

Data collected from The Nielsen Co., as distributed by Zap2it. BlipNetwork tracks non-news, non-event programming, and figures for this story reflect airing of new episodes only. For more information on the Audience Loyalty Index, click here.