Comedian Jay Leno will host a new prime-time television talk show five nights a week in 2009 on struggling network NBC after his planned retirement from his popular late-night program "The Tonight Show," NBC said on Tuesday.

The new one-hour show will air at 10 p.m., making it the first-ever program of its type to air five nights a week on prime-time U.S. TV and marking a shift in the way NBC programs the most lucrative period for TV advertising revenue.

"It just seems like after 17 years of being on 'The Tonight Show', it's fun to try something different," Leno, 58, told a news conference.

Leno's future had been in question since NBC surprised the TV business four years ago by announcing he would step down from "Tonight" in May 2009, to be replaced by Conan O'Brien, who currently hosts NBC's "Late Night" show that follows Leno.

NBC executives told journalists the deal fulfilled two goals -- keeping the popular comedian in the NBC family and stopping him from competing against them on another network.

Leno is America's favorite late-night TV chat show host with an average 4.8 million viewers this season, and he regularly beats CBS rival David Letterman in ratings.

NBC, which lags its rivals in fourth place among the major U.S. networks, said the move to prime-time TV would bring Leno a new audience in the earlier time slot.

"Clearly, today's viewers have an appetite for live, topical programming, and that's what we're bringing to primetime," said Marc Graboff, co-chairman of NBC Entertainment.

The new show, initially titled "The Jay Leno Show", will start in the autumn and will showcase many of the features that late-night viewers are familiar with, including Leno's opening monologue and comedy segments "Headlines," "Jaywalking" and "Battle of the Jaywalking All-Stars."

Leno said the exact format was still being worked out but there would be a live audience in the Burbank studio outside Los Angeles, and possibly more stunts outside the studio.

The five-day format will help NBC reduce its prime-time development and production costs in a tough economy. Leno said it would probably cost the network as much for him to do five shows a week as it would for one hour of scripted comedy or drama programming.

NBC said the earlier time should appeal to advertisers by attracting more viewers who watch the show in real time, rather than recording it and skipping through commercials.

Graboff said advertisers would get 46 weeks of original programming at the 10 p.m. hour of a show which is "totally DVR (digital video recorder) proof".

Asked what he would have done if he had failed to reach a deal with NBC, Leno replied;

"There were reports that I was going to go to ABC. But that was started by a disgruntled employee -- me."