Right now, "Lost" on ABC is trying to hold its own against "CSI: NY" on CBS in its Wednesday 10 p.m. ET timeslot. But soon, it might be trying to fight to stay out of last place with "Medium" on NBC after "Lost" posted one of its lowest overnight ratings yet, a 6.8 rating/12 share according to Fast Nationals from Nielsen Media Research.

That was more than half a million viewers compared to who tuned in the previous week to see how John Locke (Terry O'Quinn) ended up in a wheelchair. It also was about the same number less than who decided to watch a rerun of CSI instead, which picked up a 7.2/12. However, Zap2it reports that "Lost" had more total viewers.

ABC's luck with Wednesday night isn't helping "Lost" at all. Its immediate lead-in, "According to Jim" and "In Case of Emergency," had an average that was less than "Lost's" total audience -- a 3.0/5. In the 8 p.m. timeslow, with no "American Idol" on Fox, ABC did even worse, its "Great American Dream Vote" getting far less viewers than "America's Next Top Model" on The CW, which earned a 3.4/6.

ABC certainly felt it overall. The Disney network finished fourth for the night with a 4.3/7 behind Fox (9.5/16), CBS (6.6/11) and NBC (4.6/8).

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.