All but one network was down last night compared to the previous week, but one thing didn’t change: The nightly winner. Fox maintained its big Wednesday night lead courtesy of a two-hour episode of “So You Think You Can Dance.”

Fox averaged a 2.9 adults 18-49 rating and 9 share, according to Nielsen overnights, down slightly from last week’s 3.0/10 but still well ahead of second-place CBS’s 1.8/6.

All but one of the Big Four networks slipped compared to the previous week. Only ABC, whose “Primetime: Crime” was up from a 1.9 last week to a 2.1 last night, showed week-to-week gains, going from a 1.5/5 to a 1.7/5.

NBC saw the biggest decline as reality show “The Baby Borrowers” hit a new series low. The show averaged a 2.0 rating at 9 p.m., down 17 percent from last week’s 2.4.

Meanwhile, Univision tied ABC for third on the night at 1.7/5, NBC placed fifth at 1.5/5, down from a 1.8/6 last week, and CW was sixth at 0.4/1.
 
At 8 p.m. Fox was first with a 2.7 for the first half of “Dance,” followed by CBS with a 2.1 for “Big Brother,” up slightly from last week’s premiere. Univision was third with a 1.9 for “Al Diablo con los Guapos,” ABC fourth with a 1.4 for a repeat of “Wife Swap,” NBC fifth with a 1.0 for a repeat of “Baby Borrowers” and CW sixth with a 0.4 for a repeat of “America’s Next Top Model.”
 
Fox led again at 9 p.m. with a 3.1 for more “Dance,” while NBC moved to second with a 2.0 for a new “Baby Borrowers.” Univision was third with a 1.9 for “Fuego en la Sangre,” CBS fourth with a 1.7 for a “Criminal Minds” rerun, ABC fifth with a 1.4 for a repeat of “Supernanny” and CW sixth with a 0.3 for a repeat of “The Pussycat Dolls Present: Girlicious.”
 
At 10 p.m. ABC jumped into first place with a 2.1 for “Primetime,” with CBS second with a 1.7 for a repeat of “CSI: NY.” Univision was third with a 1.5 for “Don Francisco Presenta” and NBC fourth with a 1.3 for a repeat of “Law & Order.”
 
Fox also finished first for the night among households with a 5.2 average overnight rating and a 9 share, edging CBS’s 5.0/9. ABC was third at 3.4/6, NBC fourth at 2.8/5, Univision fifth at 2.1/4 and CW sixth at 0.7/1.