Jimmy Fallon got a Donald Trump bump as the GOP presidential hopeful’s appearance took “The Tonight Show” to its highest ratings for a Friday broadcast in 18 months.

NBC’s “Tonight Show” brought in 4.5 million viewers, according to Nielsen’s preliminary estimates. In adults 18-49, Fallon averaged a 1.2 rating. That was Fallon’s highest mark for a Friday broadcast since Feb. 28, 2014, shortly after his debut at the “Tonight Show” desk.

The week-one duel between Fallon and CBS’ new “Late Show” host Stephen Colbert ended with “Late Show” drawing 3.5 million viewers and 0.8 in adults 18-49. It was notable that “Late Show” held steady Friday in its 18-49 average of the past three nights despite the lure of Trump on the competition. And Friday’s “Late Show” episode was up 47% from CBS’ showing the same night last year.

Colbert’s guests on Friday included Amy Schumer and Stephen King. Trump is set to visit “The Late Show” on Sept. 22.

CBS noted that “Late Show’s” Sept. 8 premiere episode has set a new record for total streams via CBS.com and CBS apps.

The pattern after four days indicates that NBC’s “Tonight Show” will continue maintain a comfortable lead over CBS and ABC’s “Jimmy Kimmel Live,” barring big stunts or guest booking coups.

For CBS, the win with Colbert moving into “The Late Show” host slot is double-digit gains compared to the network’s performance in the time slot this time last year. And Colbert is clearly drawing a younger audience than David Letterman did in his final season.

CBS noted that “Late Show’s” Sept. 8 premiere episode has set a new record for total streams via CBS.com and CBS apps.

With the high level of scrutiny on the Fallon-Colbert competition, the biz will be eagerly awaiting the first time-shifted ratings for the new era of late-night. But that will require some patience. Nielsen’s live-plus-3 ratings for this past week are not expected to be released for another two weeks because the L3 turnaround time for the late-night daypart is much longer than it is for primetime ratings.