Mumford and Sons made their 'Saturday Night Live' debut last night (Sept. 22), performing two tunes from their sophomore effort 'Babel,' which drops Sept. 25. Talk about a high-profile way to usher in a new album.

'SNL' performances usually go one of two ways: really good or really bad. (Just ask Lana Del Rey, who turned in one of the most criticized and vilified appearances in years last January.) But from the look and sound of it, Marcus Mumford and his crew had absolutely no qualms or nerves. They did their thing and appeared completely at ease, despite the national TV audience.

The British four-piece started out quiet and slow with 'Below My Feet,' but they picked up the pace, and things intensified throughout the course of the song. They incorporated a stand-up bass and live horn section for 'I Will Wait,' further filling out the song, and all the members of the quartet were notably expressive while knuckling down on their instruments.

Viewers exposed to Mumford and Sons for the first time via this 'SNL' spot were likely impressed, and the group is bound to add to their growing fanbase.

Watch Mumford & Sons Perform 'Below My Feet'

Mumford & Sons - Below My Feet - SNL 9-20-12 by IdolxMuzic

Watch Mumford & Sons Perform 'I Will Wait'

Mumford & Sons - I Will Wait - SNL 9-22-12 by IdolxMuzic