In its first showdown with all regular competish, CBS midseason hit “Undercover Boss” took a ratings hit, but still came out on top.

The feel-good reality show held off ABC’s “Desperate Housewives” and dismissed NBC’s returning “Celebrity Apprentice,” although the latter rallied nicely to rule its second hour.

Not looking so hot in the competitive 9 p.m. hour was new Fox laffer “Sons of Tucson,” which dropped off sharply from its potent “Family Guy” lead-in. NBC fared better earlier in the evening with premiering gameshow “Minute to Win It,” which built throughout its two hours.

The combo of “Boss” and “Amazing Race” helped CBS win Sunday in all key measures, according to preliminary nationals from Nielsen. Night was the first since the start of Daylight Savings Time, which typically results in lower viewing levels, especially early in the evening.

“Boss” (3.8 rating/10 share in adults 18-49, 13.3 million viewers overall) was the night’s top-rated program in both demos and total viewers, though it declined in 18-49 by about 25% from its most recent original airing.

It may have been affected by NBC’s own unscripted look at the corporate world — “Celebrity Apprentice” — which averaged a 2.8/7 in 18-49 in the 9 o’clock hour. “Apprentice” ended up dominating its second hour (after “Undercover Boss” ended) and wound up with a solid two-hour average (prelim 3.2/8 in 18-49, 8.3 million).

Among scripted shows in the 9 o’clock hour, ABC’s “Desperate Housewives” (prelim 3.6/9 in 18-49, 11.8 million) was in line with its recent telecasts and closed the gap with “Boss,” which had more handily defeated it in their previous two matchups.

Fox was competitive at 9 p.m. with “Family Guy” (prelim 3.5/9 in 18-49, 6.7 million), but dropped off at 9:30 p.m. with “Sons of Tucson” (prelim 2.1/5 in 18-49, 4.5 million), the net’s latest attempt to score with a live-action laffer that’s thematically compatible with its animated shows.

“Tucson” tied for its timeslot’s lead in men 18-34 (2.5/8) but ran a distant fourth in 18-49.

The night’s other series premiere, NBC’s “Minute to Win It,” didn’t put up great overall numbers from 7 to 9 p.m. (prelim 1.9/6 in 18-9, 5.9 million viewers overall) but gained 1 share point in each of its final three-half-hours; and by 8:30, it was on par with ABC and Fox and pulled to within 2 shares of CBS for the demo lead.

Combined, the two-hour segs of “Minute” and “Apprentice” kept NBC competitive on the night, tying with ABC for second in adults 18-49, within a couple of ticks of CBS.

Beginning this week, hourlong segs of “Minute” will play at 8 on NBC, following newsmag “Dateline.”