The fog machine! The slow fist-pumps in the air! The singers awkwardly resting their hands on each others' shoulders! All this could only mean one thing ... 'The Sing-Off' (Wed., 8PM ET on NBC) kicked off with a group performance tonight. All 71 singers took part in a choral rendition of 'Use Somebody' by Kings of Leon, singing these words: "You know that I could use somebody/ Someone like you."

It was an amazing opening performance. But despite the teamwork and camaraderie, it's still a contest. The stakes are high -- the groups are competing for $100,000 and a recording contract. By the end of the night, only 50 singers would be left, as two groups were sent home. Who would be cut?

First episode standouts 'On the Rocks' continued their strong showing, doing an energetic version of 'Live Your Life' by Rhianna and T.I.. The judges liked it, though Ben Folds was concerned that the boys were focusing too much on being entertainers, and not enough on being actual artists.

But then, high school group 'Eleventh Hour' was eliminated, as was the most famous a cappella group in the country, the Yale University 'Whiffenpoofs.' Oh well. Back to school for both these groups. ... For the moment, only the judges control the singers' fates, but that will change as we head toward the finals. Soon enough, viewers will be able to choose their favorites -- which means the singers really will need help from somebody ... someone like you.