Yesterday’s snowfall marked one of the coldest March days in New York history, but it was one of the hottest days in Big Apple late-night television history as U2 kicked off their Letterman residency and Justin Timberlake, the Roots, Van Morrison (and “Bob” De Niro) appeared on the debut episode of Late Night With Jimmy Fallon.

Many assumed U2 would bust out single “Get On Your Boots” for their first of five nights on The Late Show with David Letterman, but with so many songs from their five star-worthy No Line on the Horizon to choose from, the band opted to bust out the rocker “Breathe” (video above). You gotta give Bono and the band credit, whether he’s singing to a stadium packed with thousands of fans or a studio audience of 250, they always go all out once they’re onstage. The song also featured Bono crooning, “Sing your heart, New York,” during the final coda, which will likely become “Sing your heart, Des Moines” or “Sing your heart, Vancouver” once U2 embark on that low-priced tour they’re planning. Of course, U2 will be back at the Ed Sullivan Theatre from tonight until Friday, so tune in for that. Horizon hits stores today and is available at the Amazon MP3 store for just $3.99.

Over on NBC in the 12:35 a.m. hour, Jimmy Fallon was attempting to fill the big shoes left by Conan O’Brien with guests Robert De Niro, Justin Timberlake, Van Morrison and house band the Roots. As it was the first night, there were more nerves than laughs — even the Roots looked a little befuddled (could they be any further away from Fallon on the stage?) Thankfully, the hour of nervous television was single-handedly rescued by Timberlake, who busted out the best John Mayer impression in the history of ever. If watching Robert De Niro sitting awkwardly on a couch while JT and Fallon talk about nothing doesn’t interest you, fast-forward the following clip to roughly the five-in-a-half minute mark for the laughs:

Related Stories:

• U2 Launch Promotional Blitz as “No Line on the Horizon” Hits Stores
• Behind the Scenes With Jimmy Fallon: Chatting With Late-Night’s New Recruit
• Jimmy Fallon Debuts “Late Night” Video Blog, Confirms House Band The Roots