The Take That star reportedly approached his friend Ben Winston for help impressing viewers after inheriting Simon Cowell's position as head panellist.
"Since Gary was given the title head judge he wanted to make sure he matched Simon in the put-down stakes," a source told the Daily Star.
"He's done a great job, and no wonder. He's got his mate Ben, who's very talented, to help out. But viewers might not be laughing now they know he's fed some of the lines."
Winston co-wrote several Comic Relief sketches for Corden's Gavin And Stacey character Smithy and this year's Fake That special, in which comedians including David Walliams and Catherine Tate spoofed Barlow and his bandmates.
"Ben's been a friend of Gary's for years and, if anything, has just been giving him moral support," a spokesperson for Barlow said. "No-one is telling him what to do."
Barlow's fellow X Factor judge Louis Walsh this week mocked the 40-year-old's "atrocious" style.
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Watch the Fake That special below: