Fox’s “American Idol” scored boffo ratings Tuesday night with its sixth two-hour edition of the season, racking up numbers on par with the previous week, which was the top-rated performance program in the show’s history.

According to preliminary nationals from Nielsen, “American Idol” (13.6 rating/33 share in adults 18-49, 33.2 million viewers overall) beat the other five broadcast nets combined by 10 shares in 18-49 during the 8-10 o’clock time period. “Idol” was up a big 17% over the same night a year ago, which was an hourlong seg.

CBS military drama “The Unit” held up best opposite the “Idol” juggernaut (4.2/9 in 18-49, 15.3 million viewers overall), continuing to look good despite a week-to-week dropoff that can at least partially be attributed to a repeat lead-in from “NCIS” (2.6/7 in 18-49, 11.5 million viewers overall). The Eye was on par at 10 with a second-place finish for “Amazing Race 9” (3.9/10 in 18-49, 9.4 million viewers overall).

Comedies continue to get mowed down by the extra “Idol,” with NBC’s hour of “Scrubs” (original and repeat) settling for a 2.7/6 in 18-49 and 5.8 million viewers overall — still easily topping ABC’s hour of original “Sons & Daughters” (1.8/4 in 18-49, 4.3 million viewers overall).

NBC’s “Law & Order: Special Victims Unit” won as usual at 10 (4.8/12 in 18-49, 13.4 million viewers overall), although both it and drama rival “Boston Legal” on ABC (2.8/7 in 18-49, 9.7 million viewers overall) were on the low side.

Preliminary 18-49 averages for the night: Fox, 13.6/33; CBS, 3.6/9; NBC, 3.1/8; ABC, 2.2/5; WB, 1/2; UPN, 0.7/2.

In total viewers: Fox, 33.2 million; CBS, 12.1 million; NBC, 8.3 million; ABC, 6.7 million; WB, 2.5 million; UPN, 1.7 million.