Many media watchers are predicting this transition will be asmoother than the last one.
"The Tonight Show" transition five years ago from Jay Leno to Conan O'Brien was a flop.
New York Times Media reporter Bill Carter has written two books chronicling the late night TV wars and sees the transition from Leno to Fallon being smoother for several reasons.
"The main difference is that Jay is on board with this. He's not fighting it," Carter says.
Carter also sees Fallon's style of comedy and his musical talents having more mainstream appeal to viewers than Conan O'brien had.
"I think they'll be more comfortable with Jimmy than they were with Conan, because I think Conan was a completely different act," he explains.
Meanwhile, Jay Leno's final act this week wraps 17 years atop late night ratings.
"He had a lot of doubters. He had a lot of critics, but the guy always won," Carter notes. "Even after they pulled him out and sent him to 10 o'clock and he came back, he won again."
Jimmy Fallon will be one of Jay's guests tonight.
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