Don't miss one song—or one note of British sarcasm—with our performance-show liveblog:

8:05 p.m.: This should be interesting. If David Cook has a secret yen for singing show tunes in the shower, now isn't the time to worry about his street cred. The estimable Top Six are dipping into the songbook of Andrew Lloyd Webber, the prolific composer of the smash musicals Phantom of the Opera, Cats and Evita, among many, many others.

"This is probably going to be the toughest night of the season," Randy opined.

Interestingly, Webber is no stranger to reality competitions, having previously gone to the dark side for the British reality show How Do You Solve a Problem Like Maria, through which he cast the lead for his West End revival of The Sound of Music.