Gwen Stefani, Blake Shelton lip sync with Jimmy Fallon

OK, so it was an in-house NBC promo for the new season of “The Voice,” but as self-promotional sketches go, Wednesday’s lip-sync contest between “Tonight Show” host Jimmy Fallon and “The Voice” coaches Blake Shelton and Gwen Stefani was pretty entertaining.

Country star Shelton quickly jumped out of his native genre by opening with Indonesian pop singer Taco’s 1983 version of “Puttin’ On the Ritz,” a track that allowed him to let his motorcycle boot-clad feet fly during the tap-dancing interlude.

That segued to Fallon’s first selection: Ellie Goulding’s “Burn,” which benefited from Fallon’s canny use of a mini flashlight for his big finish.

Stefani’s opening salvo--after dissing Fallon by thanking Jimmy Kimmel--was Carly Rae Jepsen’s “Call Me Maybe,” in which the No Doubt front woman ratcheted up the energy level and showed what a bona fide rock star has over a country singer and a musically savvy comedian when it comes to performance authority.

Shelton returned in the second round with an appropriately overly emotive run at Starship’s bombastic 1987 power ballad “Nothing’s Gonna Stop Us Now,” then turned the microphone back to Fallon for his left-field choice of bandleader Spike Jones’ loopy 1945 hit “Cocktails For Two,” replete with hiccups, sputters and other wacky sound effects.

Stefani, however, once again transcended her host’s efforts by launching into “Endless Love,” that melodramatic 1981 pop ballad by Lionel Richie and Diana Ross, for which she took Richie’s lines and brought Shelton back up to lip sync Ross’ parts.

All that was left for Fallon to do was throw in the towel and announce: “Game over!”

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