Jonathan Groff’s “Mack the Knife” on Fallon Doubles as a Sharp Tease for Just In Time
The Tony winner’s brassy late-night turn sells the nightclub sheen of Broadway’s Bobby Darin musical.
Staff Reporter September 19, 2025
Watch: “Mack the Knife” from Just In Time on The Tonight Show Starring Jimmy Fallon.
Source: The Tonight Show YouTube.
Jonathan Groff turned late night into a throwback nightclub on The Tonight Show Starring Jimmy Fallon, crooning a swaggering “Mack the Knife” backed by punchy horns and a prowling swing groove. The tight three-minute showcase functions as premium promo for his current Broadway outing, Just In Time, the immersive Bobby Darin musical at Circle in the Square.
Why this performance matters
Groff stars as Darin in Just In Time, a jukebox biomusical that transforms the in-the-round venue into a smoky club—live band onstage, audience wrapped around the action. The Fallon spot channels that aesthetic: crisp horn hits, nightclub patter, and a finale built for shareable clips.
The appearance followed advance trade buzz that the production would bring a number to the September 18 broadcast, part of a broader awareness push as the show settles into its run.
About “Mack the Knife”
The Kurt Weill/Bertolt Brecht standard—popularized by Bobby Darin—remains a calling card for the show. It lets Groff nod to Darin’s cool big-band bite without slipping into impersonation, aligning with the production’s “channel the energy, not the carbon copy” ethos highlighted in early features and reviews.
Watch & get tickets
- Watch the full Tonight Show clip: YouTube.
- Official show site (schedule, box office, media): JustInTimeBroadway.com.
- Ticketing & venue (Circle in the Square, NYC): Tickets & Box Office.
Key takeaways for fans
- Late-night performance serves as a TV-size sampler of the show’s nightclub vibe.
- Groff headlines as Bobby Darin; production is directed by Alex Timbers with an in-the-round, band-onstage setup.
- Momentum continues with active ticketing windows and strong word-of-mouth.
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