Published Monday, 25 June 2012
The Bleeding Love hitmaker, who won the contest in 2006, returned to the show as one of a string of guest judges following the departure of Kelly Rowland.
Lewis admits she came close to calling off the recording - and had to be convinced by her bosses that she was capable of criticising auditioning acts.
She tells the Daily Mirror: "The night before, I rang up and said: 'I don't wanna do it!' My management were like: 'You're doing it!' I find it hard because I like to give positive criticism."
Nicole Scherzinger has since signed up to replace Rowland on the panel, alongside Take That star Gary Barlow, Irish music mogul Louis Walsh and singer Tulisa Contostavlos.