Sara Ramirez

ABC has reason to sing: The buzzed-about Grey's Anatomy musical episode delivered big numbers, winning its timeslot and boosting the network to second place overall Thursday night.

Grey's pulled in 12.7 million viewers and improved 30 percent versus the previous week among the adults-18-to-49 demographic. It also boosted Private Practice (7.6 million) 4 percent in the demo.  Airing before Grey's, Wipeout drew 6.3 million viewers.

Still, there was no toppling American Idol and Fox. Idol's double elimination results show drew 22 million viewers, a 7 percent increase from the comparable show a year ago. Nearly 11 million of Idol's viewers stuck around for Mobbed, the new flash mob special hosted by Howie Mandel. (Fox has ordered eight more episodes.)

CBS finished third with The Big Bang Theory (11.7 million viewers) drawing the network's highest-rated half hour of the night. Rules of Engagement drew 8.2 million viewers, CSI got 12.5 million viewers and The Mentalist, with 13.9 million viewers, won the 10/9c timeslot.

NBC placed fourth as its comedy repeats averaged a little more than 2 million viewers per hour during prime time.