On paper, putting "Life On Mars" on after "Lost" seemed like a good idea. But if the first week is an indicator, it could be a killer for the cop time travel series.

"Life On Mars" earned a 4.0 rating/7 share on ABC Wednesday night, according to Fast National Ratings from Nielsen Media Research. That was down more than 25 percent from the last time it aired a new episode just before Thanksgiving, when ABC was still airing it against "Eleventh Hour" on Thursday nights.

But the new Wednesday slot was not so busy. In fact, "Mars" only had to compete with a rerun of "CSI: NY" as well as a new episode of "Law & Order" on NBC, both of which beat "Mars" handedly. "Law & Order" drew a 48 percent larger audience than "Life On Mars" despite having a rerun as a lead-in.

"Mars" can't even blame that for its problems, because leading into it was an all-new episode of "Lost," which drew a 6.4/10, according to Zap2it, matching its second hour from its season premiere last week. That means "Mars" lost nearly 38 percent of "Lost's" lead-in audience.

While "Lost" competed well with "Criminal Minds" on CBS, the network was airing a rerun. It finished with nearly 10 percent fewer viewers than the second episode of "Lie to Me" on Fox, which won the hour.

"Lost" is definitely struggling to find its audience. The first three episodes are down more than 17 percent from its overnight average a year ago, and is being beat on a weekly basis by shows like "Fringe" on Fox, which has not benefited from the buzz that "Lost" receives.

"Knight Rider" also aired for NBC, earning a 3.8/6, completely outmatched by "American Idol" on Fox. It did beat reruns on the other channels as well as a CBS news special.

"Knight Rider" was up about 6 percent from last week, but is still 22 percent off its series high and 31 percent down from the average overnight rating of "Bionic Woman," which aired in the same time slot.

ABC and NBC battled for third place among all the networks for Wednesday night with NBC leading in households, but ABC stepping ahead in viewers. Fox, of course, won the night thanks to "American Idol" with an 11.1/17 average.

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.

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