Dermot O'Leary is stepping in to replace Sir Terry Wogan on this Friday's Children in Need after he pulled out for "health reasons".
It will be the first time Sir Terry will not have hosted it since its 1980 launch.
Sir Terry, 77, is having a procedure on his back and is understood to have withdrawn in line with doctors' advice.
The show is also due to be presented by Tess Daly, Rochelle Humes, Nick Grimshaw and Fearne Cotton.
Many stars are expected to feature in the show including One Direction, actress Dame Helen Mirren, former Doctor Who star David Tennant, Sherlock actor Martin Freeman and singer Ellie Goulding.
Former X Factor presenter Dermot O'Leary has congratulated the show's new hosts Olly Murs and Caroline Flack.
X Factor host Dermot O'Leary has praised the impact of Sharon Osbourne on the new series, saying she has brought the best out of the other judges.
He told ITV's Daybreak: "She has brought Louis back into prominence, it's almost like he is an old sheepdog who has just woken up by the fire.
"Gary (Barlow) has a great sense of humour, she brings that out in Gary and her and Nicole are close."
He added that the show had a more "nostaligic feel" this year and that is was much "warmer" than previous series.
The X Factor judges – including comeback judge Sharon Osbourne – are back together ahead of the first filmed auditions of the new series.
Osbourne, who was on the show from 2004 to 2007 and replaces Tulisa Contostavlos, will feature alongside Louis Walsh, Nicole Scherzinger and Gary Barlow.
Although preliminary auditions have already taken place, the judges start their first day on the programme today.
The presenter opened two Fishy Fishy eateries on the south coast with one based in Poole, Dorset and the other in Brighton, Sussex.
O'Leary told the newspaper the Brighton outlet, which employs 25 staff, was doing fine but that he had to close the Poole restaurant, leaving 13 people without jobs.
He said: "Sadly, we decided that Fishy Fishy Poole should cease trading owing to the current financial climate. Fishy Fishy Brighton continues to trade as normal.”
X Factor host Dermot O'Leary has revealed he bumped into Morrissey as he checked into his honeymoon hotel - and the former Smiths frontman told him his marriage would not last.
O'Leary tied the knot with long-term girlfriend Dee Koppang last month in a ceremony at a church in Kent.
He said the surly singer delivered his gloomy verdict when he spotted him in the courtyard of his hotel in Rome.
In an interview for tonight's Jonathan Ross Show on ITV1, O'Leary said he approached Morrissey, whom he had previously interviewed for his BBC Radio 2 show: "I went over and I said, 'It's lovely to see you', and he said: 'Really? I'm sure you'd say the same thing to Barry Manilow or Gary Barlow'.
"I said, 'No it is. Morrissey, I'm here on my honeymoon', and he said, 'It won't last, these things never do'."
Dermot O'Leary has signed up to return to The X Factor, hosting the show for a sixth series.
The popular presenter is the latest addition to the line-up for the programme which returns later this year, with auditions beginning next week.