There was the sense going into last night’s season premiere of “Alias” that this was the last chance for the critically acclaimed but ratings-challenged ABC spy drama.
   ABC moved the show from Sundays to Wednesdays at 9 p.m., following its mega-hit “Lost,” in a last effort to save the show. If it couldn’t find an audience there, it wouldn’t survive anywhere.
   It looks like the move worked. 
   The show’s two-hour season premiere averaged an impressive 6.8 rating among adults 18-49 last night, according to Nielsen overnights, retaining 82 percent of “Lost’s” lead-in. That helped ABC to a dominating 7.3 average for the night, nearly double second-place CBS’s average.
   Elsewhere last night, the premiere of NBC’s new show “Sports Illustrated Swimsuit Model Search” did nowhere near as well, averaging a 2.8 18-49 rating. The show did gain audience during its second half, though, and did better the average of the 8 p.m. time slot’s former occupants, “Hawaii” and “LAX,” by nearly a third.
   ABC provided a marketing blitz for the “Alias” premiere, including a heavy saturation of ads on sister network ESPN and the internet. While “Lost” has been gaining viewership steadily through the year, “Alias” wasn’t guaranteed that audience would stick around.
   After all, this is the fourth season for a very intricately plotted show. Some wondered if new viewers would tune in at the risk of being confused.
   But ABC did a nice job of playing up the new direction of the show, assuring viewers that they could start cold. And “Alias” delivered a huge ratings increase from last season’s 3.5 average rating.
   Its 16 million total viewers average doubled last year’s 8 million average. It marked the largest-ever audience for the fourth-year show, outdrawing even the post-Super Bowl episode in 2003.
   The show did lose some audience through the night, but that was expected; it faced strong competition at 10 p.m. from new episodes of “Law & Order” and “CSI: New York.” But “Alias” trumped their 4.5 and 4.4 ratings, respectively, with a 6.2.
   NBC’s debut of “Model Search” didn’t witness nearly the success of the network’s two other debuts this week, Monday’s “Medium” (6.3) and Tuesday’s “Committed” (4.5). Episodes of “The West Wing” and “Law & Order” managed to only pull the network to a third-place finish in the demo, with a 3.6 average rating and 9 share. ABC was easily No. 1 with a 7.3 average and 18 share, followed by CBS at No. 2 at 3.7/9. Fox finished fourth at 3.5/8, and the WB and UPN tied for fifth at 1.2/3.
   “Lost” led the way at 8 p.m., averaging an 8.3 18-49 rating, the highest-rated show of the night. Fox finished second that hour with a 2.9 average for “That ‘70s Show” (3.1) and “Quintuplets” (2.7) and NBC third with its 2.8 average for “Model Search.”
   At 9 p.m. ABC’s “Alias” averaged a 7.3 18-49 rating for the first hour of its premiere. Fox averaged a 4.1 rating that hour for “Nanny 911,” tying it for second with CBS for the comedies “King of Queens” (4.3) and “Center of the Universe” (3.9). NBC’s “West Wing” was fourth that hour with a 3.7 average rating.
   ABC also took the night among households, finishing with a 10.9 average rating and 16 share. CBS finished second at 7.8/12, NBC third at 7.7/12, Fox fourth at 5.2/8, UPN fifth at 2.0/3, and the WB sixth at 1.7/3.