And Robbie wasn't having any of it, using an interview with The Sun's TV magazine in order to defend his friend and hit back at Nicole following the insults.
He told the magazine, "Nicole keeps calling him ‘Gary Borelow’ – well she’s Nicole S**tsinger!
"Gary is the most talented out of the lot of them... the captain. He is doing a great job as head judge. He's funnier this season than the last, which is great because he's way more funny than me."
Robbie added, "I've still got my Gary Barlow crush. I love him to bits."
Gary and Robbie, back together on The X Factor.
And Robbie needs to stay on Gary's good side - the pop star recently admitted that he wants to join Take That again, as he feels he's getting too old to do it solo.
Speaking to The Daily Star about his ex-bandmates, Robbie said, "We promised each other we would soon meet up for dinner and look through our agendas.
"It would be beautiful if I could do a bit of both. This doesn't seem impossible if we can plan it well."
Below, listen to Robbie's upcoming new single, 'Different':
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