X Factor: Nicole Scherzinger 'hardest working' judge
X Factor presenter Dermot O'Leary has praised Nicole Scherzinger as "the best judge" on this year's panel.
The new series launches this weekend on ITV with a revamped line-up.
Speaking at the show's London press launch, O'Leary said: "She works the hardest."
Scherzinger said: "I'm very competitive, very picky, I really care. Otherwise, if you don't put everything into it and everything isn't as great as it can be, why do it?"
This year's series has had an overhaul, with O'Leary returning to present after a year off and all three of the original judges returning.
Louis Walsh, Simon Cowell and Sharon Osbourne were on the judging panel on the show during its first series in 2004.
Former Pussycat Dolls singer Scherzinger is set to join them, returning after her two previous stints as a judge on The X Factor UK, and one in the US.
"I'm actually here because of Louis, he's the one who wanted me back," she said, crediting her fellow judge with championing her to Cowell.
Walsh said: "Nicole works really hard, takes it seriously... she wants, more than anybody else, to win again."
But her return to the panel was not without controversy.
Scherzinger had been expected to continue working with Andrew Lloyd Webber in a stage production of Cats.
She played the role of Grizabella when the show was in London's West End last year, and had been rumoured to continue in the role this year when the show opened on Broadway.
But Lord Lloyd-Webber said she dropped out of continuing in the role to do X Factor instead, leaving him "furious".
Speaking at the London launch, Scherzinger suggested they had left that behind them and are now on good terms.
"I know he and [his wife] Madeleine always watch the show so hopefully they still will, and I did a show in Austria with him recently so it was all good.
"I can't wait to work with him again... but Simon's loving it," she added, referring to the apparent feud.
And Scherzinger isn't the only person who Louis helped get on to this year's X Factor.
Former contestant Rylan Clark-Neal will host sister show the Xtra Factor on ITV2 this year, alongside Radio 1 presenter Matt Edmondson.
"Louis did get me the job... he bullied Simon for about three years," Clark-Neal said.
Walsh explained: "Simon doesn't know Rylan as well as we do because he wasn't there that year [when Clark-Neal was a contestant].
"But Nicole, Sharon and I worked with him on the show - we know how good and quick and intelligent he is."
Last year's X Factor was the least successful in the ratings since the first series in 2004 - something that many fans and critics put down to the panel being too young and lacking chemistry.
Walsh himself said that "the show wasn't really good last year" - adding that he lobbied Cowell to make changes to this year's show.
All eyes now will be on the ratings to see whether fans return to see three of the original panel back together.
Audiences have been falling since The X Factor's 2010 peak, when more than 17m people tuned into the final to see Matt Cardle crowned the winner.
But fast forward to 2015 - and an average of 8.4m watched the final, meaning the show lost about half its audience since 2010.
Speaking to the BBC about last year's series, Walsh said: "I was checking the ratings every week and saw it was getting lower.
"I was delighted. I watched the show and I didn't think it was as good as it used to be."
By bringing back so many familiar faces, Cowell clearly hopes The X Factor can recapture its former glory.
But it will face stiff competition for much of it run from Strictly Come Dancing on BBC One, which has been firmly ahead in the ratings in recent years.
Strictly is once again putting up a strong batch of contestants - with Ed Balls, Louise Redknapp and Greg Rutherford among this year's celebrities.
The X Factor may be pulling out all the stops in the hope of securing more series in the future, but it is going to have a tough fight on its hands.