ABC, perhaps boosted by a stronger showing in the final half-hour of primetime, has opened the latenight season on a strong note.

Both “Nightline” and “Jimmy Kimmel Live” gained vs. the opening frame of last year while all of their latenight talkshow competition — including Jay Leno on NBC and David Letterman on CBS — showed declines.

News vet “Nightline” was the top-rated latenight program in all key categories for the week of Sept. 19-23, marking the first time it has topped both CBS and NBC in demos for premiere week, according to Nielsen. The 11:35 p.m.-midnight show averaged 1.25 million adults 18-49 (even with last year), 1.60 million adults 25-54 (up 2%) and 3.85 million viewers overall (up 7%).

And following “Nightline,” Kimmel’s show drew 790,000 adults 18-49 (up 5%), 918,000 adults 25-54 (up 13%) and 1.82 million viewers overall (up 8%). The total-viewer count is the second largest to date for a premiere week of “Jimmy Kimmel Live.”

Elsewhere, NBC’s “Tonight Show With Jay Leno” held slim advantages over CBS’ “Late Show With David Letterman” in 18-49 (1.07 million vs. 1.05 million) and 25-54 (1.40m vs. 1.34m), with the Peacock series also leading in total viewers (3.64m vs. 3.22m). “Tonight” slid by 20% in 18-49, 10% in 25-54 and 4% in total viewers, suggesting an older skew this year, while “Late Show” was off by about 15% across the board.

At 12:35 a.m., NBC’s “Late Night With Jimmy Fallon” led over CBS’ “Late, Late Show With Craig Ferguson” in 18-49 (695,000 vs. 607,000) and total viewers (1.69m vs. 1.51m), with “Fallon” down 16% in the demo and “Ferguson” off 7%.

In the 10:30 p.m. half-hour leading into primetime during premiere week, CBS (2.74 rating) and ABC (2.70) were neck and neck in 18-49 weeknight averages, with the Eye dipping by 7% while the Alphabet surged by 27%. NBC lagged at 1.96 (down 8%).

And in 25-54, CBS led the way (3.80 rating, down 7%), followed by ABC (3.36, up 19%) and NBC (2.44, down 4%).

On the cable side, no latenight talkshow saw gains vs. last year. Top-rated in 18-49 was Comedy Central’s “Daily Show” (946,000 adults 18-49 and 1.67 million viewers overall).