Graham Norton is to set the world record for the most questions asked on a TV chat show.
The presenter is preparing for the challenge in aid of Comic Relief and will see him asking questions to celebrities including Elle Macpherson, Keith Lemon, Jimmy Carr and Martin Freeman.
The show will begin tonight at 7pm on BBC3 and will last for six or seven hours.
There is no current World Record for the most questions asked in a TV chat show, so Norton is certain to enter the record books.
He said: "David Walliams swam the Thames, John Bishop endured a week of hell and Eddie Izzard ran marathon after marathon after marathon. I am hoping to join this elite group of celebrity fundraisers by doing what I do best - sitting on my backside and talking."
In an interview with the Sun, Norton said: "It is not going to be easy, but at least I won't be physically hurt. I do tend to have quite a lot of energy most of the time, but in the worst-case scenario, I can always get the guests to interview each other if I nod off."
Other guests include Ronnie Corbett, Sarah Millican, Lee Mack, Keith Lemon, James Nesbitt, Paddy McGuinness, Heston Blumenthal, Louis Smith; Aston from JLS, Got To Dance Judges Ashley Banjo and Kimberley Wyatt, Warwick Davis, Alex Jones, Steve Jones, Russell Tovey and Kirstie Allsopp.
Viewers encouraged to participate
There will also be performances by Example, Paloma Faith, Hurts and Laura Mvula.
Viewers are able to participate in the evening by submitting questions to ask guests on Twitter or on BBC3's Facebook page.
The Guinness World Record for longest TV quiz programme is held by German broadcaster 9Live for a 2003 show that lasted 52 hours and 45 minutes. During the show, approximately 1,500 questions were asked.
The record for the longest quiz master marathon is 32 hours and 15 minutes set by UK's Gavin Dare, who asked 3,668 questions at The Goff's Oak Public House in Hertfordshire.
Spain's Pedro Ruiz holds the record for the longest television interview, which lasted 12 hours and 30 seconds. The 2009 interview saw Ruiz interviewing a host of national celebrities.
Comic Relief's Big Chat with Graham Norton is on BBC tonight at 7pm (Thursday).