Take That star Gary Barlow admitted he had been taking advice from X Factor supremo Simon Cowell before stepping into his shoes on the show.
The singer said it was "a little strange" joining the judging panel on the hit ITV1 programme.
A record number of viewers - a peak of 12.6 million - got their first look at Gary and fellow debutants Kelly Rowland and Tulisa Contostavlos on Saturday night as they joined show veteran Louis Walsh on the panel.
The trio replaced Cheryl Cole, Dannii Minogue and Simon, who is busy with the US version.
Gary said: "I spent a little bit of time with Simon warning me what it's going to be like and how to be and he said what everyone said to me, 'just be yourself'.
"It's been tough, it really has, I think the hardest thing is learning to really be you on camera."
Fellow judge Tulisa said her new role was her "dream job".
In comments on the show's official website, she said: "I think it was about three years ago now, I was sitting at home watching X Factor at Christmas and I think I turned around to my dad and said 'I could do that'.
"I said 'that is actually my dream job' and then all of a sudden three years later I got the call and here I am now, a judge on X Factor."
Among the acts on the show on Saturday were cheeky 18-year-old Frankie Cocozza from Brighton.
The teenager told the panel he had the names of seven different girls he met on holiday tattooed on his backside and then bared all to prove it.
Also making an appearance was shy Janet Devlin.
The singer from Northern Ireland went down a storm with her version of Elton John's Your Song.
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