Tonight Show host Jay Leno and heir apparent Jimmy Fallon documented their own tense rivalry over comedy's most-coveted gig in musical form in a bit on both late night shows Monday.

The bit -- which was reportedly Fallon's idea -- began with a phone call between the hosts, with Leno forlornly telling Fallon, "I'll live I've been through this before. I'll admit I'm a little sick of all this."

After Leno reassured Fallon they would still be friends regardless of business, the two launched into a music duet parodying West Side Story's Tonight.