Post-premiere ratings for pretty much all new shows this fall have drifted downward, but CBS rookie “The Mentalist” is an exception, logging its best scores yet in its sixth outing.

The crime drama starring Simon Baker seemed to benefit from the absence of firstrun drama competish from fellow frosh “Fringe” on Fox, rising 8% above its previous high rating among young adults. Other shows in the hour were on the high side as well.

For CBS, “The Mentalist” (3.9 rating/9 share in adults 18-49, 16.07 million viewers overall) achieved highs across the board and built on its “NCIS” lead-in (3.4/9, 17.26m) by a best-yet 15% in 18-49. It won its hour among adults 25-54 (5.4/12) for a fourth straight telecast.

CBS, which also saw “Without a Trace” match or set some highs at 10 o’clock (2.9/8 in 18-49, 12.19m), drew its best 18-49 average since last December. Fox still won out in 18-49 for the net thanks to a dominant demo perf at 8 from “House” (5.4/14, 13.50m).

“Fringe,” which has been winning its 9 o’clock timeslot in 18-49, aired a repeat (fourth-place 2.3/6 in 18-49, 5.66m), enabling auds to check out other shows.

In addition to “The Mentalist,” ABC’s “Dancing With the Stars” results show (3.9/9 in 18-49, 17.45m) and NBC’s “The Biggest Loser” (3.2/8, 8.14m for its two hours) hit season highs, and CW’s “Privileged” (0.9/2, 1.92m) was up over its most recent seg.

The 9 o’clock hour on Tuesday is shaping up to be the most competitive among the Big Four. It wouldn’t be surprising to see ABC, CBS, NBC and Fox all finish within a few ticks of each other when they next all go head to head on Nov. 11.