After challenging the groups with hip-hop, 'The Sing-Off' (Mon., 8PM ET on NBC) threw them a double-whammy this week by having them tackle one song in the classic rock genre and another in country. It was a challenge that would truly show who could be the most versatile.

!!SPOILER ALERT!!

Urban Method was probably the group most people were immediately concerned about, as neither genre suits their sensibilities. In fact, they even added a rap to their rock track, 'Here I Go Again,' which was a little odd.

Ben Folds said they worked their way out of a slump with their country song, though. They certainly wailed on 'Before He Cheats,' with the girls showing a confidence Sara Bareilles hadn't seen from them yet.

It was enough to keep them in the competition, as the "all-star" all-female group Delilah couldn't avoid pitch problems and just really hasn't been able to recapture the magic of 'Grenade' all season -- though they've been chasing it while inexplicably not putting Amy in the lead for most performances. That was the secret formula to their success in that number.