With their franchise reality shows going head-to-head in prime time Wednesday night, two networks staged a close battle for the night's ratings crown, based on Nielsen overnights for the key 18-49 demo. TVbytheNumbers.com reports that CBS inched ahead of Fox for the No. 1 spot, while CBS's "Survivor" won the head-to-head battle with Fox's "American Idol."

ABC, meanwhile, again had the top broadcast show in Wednesday prime, with "Modern Family."

"Survivor" delivered a 2.5 average in 18-49 at 8 p.m. for CBS, ticking up 4% from a week ago. Fox's two-hour "Idol" marked the show's 500th episode, and celebrated with a 24% improvement over last week, registering a 2.1.

Leading out from "Survivor," the season finale of CBS's "Criminal Minds" came through with a 2.7 average in the 18-49 demo, climbing 17% from a week ago. CBS wrapped up prime time with a "CSI" repeat, which pulled a 1.5 average.

"Modern Family" led the way for ABC with a 3.1 average in viewers 18-49, up 7% from a week ago and the best demo number Wednesday night in broadcast prime. The rest of the ABC lineup was also mostly up, including "The Middle," up 19% with a 1.9; "Suburgatory," up 15% with a 1.5; and "Nashville," up one-tenth of a point from last week with a 1.3.

ABC's "Mixology" held steady with a 1.3 average in 18-49.

NBC's drama lineup didn't move much, except for "Chicago PD," which rose 14% in the 18-49 demo from last week's series low, delivering a 1.6 average. "Revolution" and "Law & Order: SVU" both matched last week's numbers — a 1.1 for "Revolution" (a series low), and a 1.5 for "SVU."

For prime time overall, CBS led the way in the 18-49 demo wtih a 2.2 average, ahead of Fox (2.1 average), ABC (1.7), NBC (1.4) and Univision (1.1). CBS also won total viewers, averaging 9.9 million to top Fox (8.8 million), ABC (5.8 million), NBC (5.1 million) and Univision (2.7 million).