“How Soon is Now?” The Smiths cryptically wondered on their self-titled 1984 debut. I can name that tune in one shimmering, echo-pedaled guitar note. So when ex-Smiths guitarist Johnny Marr performed the song last week on “Late Night With Jimmy Fallon” in support of his first solo disc, “The Messenger,” I witnessed both greatness and sacrilege. There was that riff, making my head swim. But the vocals, those can only ever be Steven Patrick Morrissey’s.

Since The Smiths split back in 1987, Morrissey’s fallen-angel croon has held up seven very decent solo records. One could almost think he didn’t need Marr much after all. Marr’s done fine, too, working with the Pretenders and members of New Order, Radiohead and Modest Mouse over the years.

Marr is now touring behind “The Messenger,” and he also played the title track on “Fallon” — shades of Echo and the Bunnymen at their poppiest. The album as a whole is strong and fun, and Marr’s lead vocals fit well into the Britpop tunes that recall Pulp and The Charlatans UK.

Marr isn’t Morrissey, and he doesn’t need to be. He doesn’t need to bring back The Smiths. He’s Johnny Marr.