Late Night host Conan O'Brien will take over the 11:35 p.m. time-slot on Monday, June 1.

Comedian Jimmy Fallon will succeed O'Brien, 45, on Late Night in March or April of 2009 after a stint of web-only editions.

"I hope to make it the best show and a great show for everyone to choose me to fall asleep during," Fallon, 33, said in May.

There has been much speculation that Leno, 58, will jump to another network when his NBC gig ends next summer.