The network closed out a frenzied come-from-behind sweeps win among adults 18-49 Wednesday night by jumping 0.4 points in the final two nights to overtake Super Bowl carrier CBS.

Some had expected CBS, which led up until Wednesday night, to hold off Fox. After all, the Super Bowl carrier has won the last two Februarys.

But the unexpected success of Fox’s new Foxworthy-hosted show “Are You Smarter Than a 5th Grader?” gave the network an extra edge this week.

Fox finished February with an average 5.2 rating and 13 share, and CBS was second with a 5.0/13. Entering the final night, Fox trailed CBS by 0.1.

ABC took third at 3.9/10, followed by NBC at 2.9/8, Univision at 1.7/4, the CW at 1.4/3, Telemundo at 0.4/1, and Telefutura at 0.3/1.

Fox’s late surge was expected. The network aired five hours of “American Idol” last week and four hours this week, more than double what it usually has on the schedule.

But the difference maker was “Smarter,” which had the biggest debut for a Fox show in 13 years Tuesday (excluding a post-Super Bowl "Family Guy"), holding onto a record 92 percent of “Idol’s” audience.

You might expect the network could toss anything on after “Idol” and still draw huge numbers, but that hasn’t proven true. Several failed comedies have cycled through the post-“Idol” slot, losing half its audience.

Last year the reality show “Unan1mous” averaged a 6.0 in 18-49s airing out of “Idol.” “Smarter” has averaged 10.5 through two outings.

“Smarter” seemed like little more than a gimmick when it launched, a way for Fox to give top performer “House” a brief rest so as to save more episodes for the critical May sweeps.

But the brilliance of the show is that, like “Idol,” it is family entertainment. Past sitcoms have flopped because they’re aiming at older viewers, and it’s families that really help power “Idol.”

If there’s a show on afterward that they can all watch together, unlike workplace comedy “The Loop” or more sophisticated fare like “Wanda at Large,” they’re likely to tune in.

Plus, having Foxworthy, the popular star of the WB’s late “Blue Collar TV” as well as a string of highly rated Comedy Central specials, certainly helps as well.

The show asks contestants to answer questions better suited to elementary school students, and they compete in subjects like social studies, math and art. The amusing part is that they don’t always get the answers right.

Fox ends sweeps up 2 percent over last year in 18-49s. CBS grew 43 percent, spurred by the Super Bowl. But even excluding the big game’s numbers, the network was up a solid 6 percent.

ABC, which carried last year’s Super Bowl and won last year’s February sweeps, ended down 26 percent. Excluding Super Bowl, it fell 5 percent, with the Academy Awards, which aired after sweeps last year, offsetting the absence of “Dancing with the Stars.”

NBC fell 41 percent compared with last year, when it carried the Winter Olympics. Excluding those, it was still down 12 percent.

The CW was flat to last year’s WB rating and up 27 percent compared with UPN.

Two years ago, Fox won the February sweeps by a large margin partly on the strength of Super Bowl, in which quarterback Brady's New England Patriots beat the Philadelphia Eagles.